We are searching data for your request:
Upon completion, a link will appear to access the found materials.
Does the brain really function like a computer as in, ultimately every response is related to a binary sequence based on whether particular neurons fire or not?
First of all, I would like to point out that making analogy between digital computers and the brain is often very misleading.
That being said, my answer is, some scientists believe so, some don't.
Several things to consider:
Some neural systems are not spiking. C. elegans for example has a nervous system that is entirely analogue. Human nervous system also contains neurons with graded responses (mostly in the sensory front-end though).
Spiking neurons may be binary at each time point, but time itself is continuous. Firing at 0.003 seconds later can represent something different. (in contrast to the usual synchronous digital architecture of computers)
The neuron doctrine is sometimes challenged. Glial cells that do not fire may have important functions for information processing. See:
- Bullock, T. H., Bennett, M. V. L., Johnston, D., Josephson, R., Marder, E., and Fields, R. D. (2005). The neuron doctrine, redux. Science, 310(5749):791-793.
While action potentials are usually binary, you should note that synaptic communication between neurons is generally not binary. Most synapses work by neurotransmittors, and this is a chemically mediated graded response that, for example, act on voltage-gated ion channels. So even though action potentials are often binary, communication between neurons are most often not, and action potential firing can involve the integration of synaptic information from many different neurons. Therefore, the brain as a whole cannot be reduced to a binary system.
See this as a complement to @Memmings answer.
John vonNeumann, the famous computer scientist, tackled this idea in his last book, 'The Computer and the Brain.' He personally landed on the side of the brain being a binary system, due to the behavior of neurons which either fire or do not fire.
While that is an important observation, and will have significant consequences to people trying to create artificial brains within computer systems, I think a more important observation has to do with computational complexity. It is very easy to build systems which, at least theoretically, have the potential to be universal computers. From that fact, it is fairly trivial to see that whatever definitions you choose to work with in terms of brain input and output (sensory nerve cells feeding electrical impulses from organs of perception being a possible definition of 'input' and propagated impulses to muscles, or changes in the neural structure itself being possible definitions of 'output' for example), yes it is possible to construct a binary system which can perform the same calculations as a human brain.
However, there is a catch. Because it is impossible to perfectly know the complete state of the brain, and because any degree of inaccuracy in the starting state of the binary system, no matter how small, will cause the behavior of the binary system to diverge completely from the behavior of the specific brain being modelled, it is reasonable to say that no particular individual brain can be reduced to a binary system.
as far as I know the brain processes data in stages the neurons themselves are not purely binary as in a computer in that every action has a predetermined output. the neuron response tends to be goverened by sigmoid function output and hence the use of this function in artificial neural networks. further, the synapses have strengths that is depended on the amount of neurotransmitter in there which obviously varies from cell to cell and even in the same cell and hence one speaks of the probability of a neuron firing given a certain stimulus. additionally the neurons from sensory organs fire pulses at a frequency that increases with the strength of the stimulus. furthermore, the data from sensors is processed in layers of neurons lower layers have rapidly firing neurons whule higher layers fire at much lower rates.
you also have to consider the fact that the brain is actually a complicated network of "recurrent" neurons meaning that the output is fedback as an input and this is different from simple computer gates such as AND gates or XOR gates it is similar to counters may be but obviously on a very bigger scale. one more point is that recurrent neural networks have built in memory that enables the pattern recall and recognition and so the study of the brain as a binary system is very complicated and will fail to explain how the brain works.
on the macro scale the human brain operates as a bayesian inference engine more or less I mean when it comes to thinking and inference i.e. it relies on probabilities and knowledge gained from past experiences to deal with current problems and new data
It's theoretically possible, because all information can be well approximated/copied in binary, and it's practically impossible because of size, energy, and program size/depth.
A fly brain is <1mm wide and an intel fly brain equivalent is >1000mm wide… much slower than the fruit fly. (Thats why flies see your hand coming in slow-mo).
This intel chip has as many neurons as a slug, far less than a fly: https://www.cnet.com/google-amp/news/intel-packs-8-million-digital-neurons-onto-brain-like-pohoiki-beach-computer-loihi-chips/
he binary model has to include "chemical modelling" and "physical modelling" like a graphics card which models light and creatures as binary.
Except that there is an added issue: processing speed. The brain can grow direct connections which are very fast. Silicon signals have to travel 1000 times further for every calculation.
2d chips take as much space as a skyscraper and a small nuclear station for energy, and future mythical 3d transistors would take space and would be slower because they require direct chemical processing and flexible internal connection to be as fast.
AI is very performant and is one of the future paradigm changes like "internet/mobile phone / electric car / AI "
human brain is strictly digital device using defined action potentials (0 volt as logical 0 and specified (fixed) voltage potential as logical 1). these two potentials work same way as complex logic gates systems. brain processes all types of analog-like variations (signal amplitude or response strength) as very short time based sums of logic gates operations. there is no other applicable description of brain functionality
COVID-19: Scientists identify human genes that fight infection
Scientists at Sanford Burnham Prebys have identified a set of human genes that fight SARS-CoV-2 infection, the virus that causes COVID-19. Knowing which genes help control viral infection can greatly assist researchers' understanding of factors that affect disease severity and also suggest possible therapeutic options. The genes in question are related to interferons, the body's frontline virus fighters.
The study was published in the journal Molecular Cell.
"We wanted to gain a better understanding of the cellular response to SARS-CoV-2, including what drives a strong or weak response to infection," says Sumit K. Chanda, Ph.D., professor and director of the Immunity and Pathogenesis Program at Sanford Burnham Prebys and lead author of the study. "We've gained new insights into how the virus exploits the human cells it invades, but we are still searching for its Achille's heel so that we can develop optimal antivirals."
Soon after the start of the pandemic, clinicians found that a weak interferon response to SARS-CoV-2 infection resulted in some of the more severe cases of COVID-19. This knowledge led Chanda and his collaborators to search for the human genes that are triggered by interferons, known as interferon-stimulated genes (ISGs), which act to limit SARS-CoV-2 infection.
Based on knowledge gleaned from SARS-CoV-1, the virus that caused a deadly, but relatively brief, outbreak of disease from 2002 to 2004, and knowing that it was similar to SARS-CoV-2, the investigators were able to develop laboratory experiments to identify the ISGs that control viral replication in COVID-19.
"We found that 65 ISGs controlled SARS-CoV-2 infection, including some that inhibited the virus' ability to enter cells, some that suppressed manufacture of the RNA that is the virus's lifeblood, and a cluster of genes that inhibited assembly of the virus," says Chanda. "What was also of great interest was the fact that some of the ISGs exhibited control across unrelated viruses, such as seasonal flu, West Nile and HIV, which leads to AIDS."
"We identified eight ISGs that inhibited both SARS-CoV-1 and CoV-2 replication in the subcellular compartment responsible for protein packaging, suggesting this vulnerable site could be exploited to clear viral infection," says Laura Martin-Sancho, Ph.D., a senior postdoctoral associate in the Chanda lab and first author of this study. "This is important information, but we still need to learn more about the biology of the virus and investigate if genetic variability within these ISGs correlates with COVID-19 severity."
As a next step, the researchers will look at the biology of SARS-CoV-2 variants that continue to evolve and threaten vaccine efficacy. Martin-Sancho notes that they have already started gathering variants for laboratory investigation.
"It's vitally important that we don't take our foot off the pedal of basic research efforts now that vaccines are helping control the pandemic," concludes Chanda. "We've come so far so fast because of investment in fundamental research at Sanford Burnham Prebys and elsewhere, and our continued efforts will be especially important when, not if, another viral outbreak occurs."
Additional study authors include Lars Pache, Anshu P. Gounder, Courtney Nguyen, Yuan Pu, Heather M. Curry, Paul D. De Jesus, Ariel Rodriguez-Frandsen and Xin Yin at Sanford Burnham Prebys. Other authors include Mary K. Lewinski, Charlotte A. Stoneham, Aaron L. Oom, and John Guatelli at the University of California at San Diego and the VA San Diego Healthcare System Mark Becker, Thomas J. Hope and Judd F. Hultquist at the Northwestern University Feinberg School of Medicine Dexter Pratt, Christopher Churas, Sara B. Rosenthal, Sophie Liu, Fan Zheng, Max W. Chang, Christopher Benner, Trey Ideker and Alan M. O'Neill at the University of California San Diego Lisa Miorin, Matthew Urbanowski, Megan L. Shaw and Adolfo García-Sastre at the Icahn School of Medicine at Mount Sinai Stuart Weston and Matthew B. Frieman at the University of Maryland School of Medicine and Chunxiang Wu and Yong Xiong at Yale University.
The endocannabinoid system, broadly speaking, includes:
- The endogenous arachidonate-based lipids, anandamide (N-arachidonoylethanolamide) and 2-AG these are known as "endocannabinoids" and are physiological ligands for the cannabinoid receptors. Endocannabinoids are all eicosanoids. 
- The enzymes that synthesize and degrade the endocannabinoids, such as fatty acid amide hydrolase or monoacylglycerol lipase.
- The cannabinoid receptorsCB1 and CB2, two G protein-coupled receptors that are located in the central and peripheral nervous systems.
The neurons, neural pathways, and other cells where these molecules, enzymes, and one or both cannabinoid receptor types are all colocalized collectively comprise the endocannabinoid system.
The endocannabinoid system has been studied using genetic and pharmacological methods. These studies have revealed that cannabinoids act as neuromodulators    for a variety of processes, including motor learning,  appetite,  and pain sensation,  among other cognitive and physical processes. The localization of the CB1 receptor in the endocannabinoid system has a very large degree of overlap with the orexinergic projection system, which mediates many of the same functions, both physical and cognitive.  Moreover, CB1 is colocalized on orexin projection neurons in the lateral hypothalamus and many output structures of the orexin system,   where the CB1 and orexin receptor 1 (OX1) receptors physically and functionally join together to form the CB1–OX1 receptor heterodimer.   
Expression of receptors Edit
Cannabinoid binding sites exist throughout the central and peripheral nervous systems. The two most relevant receptors for cannabinoids are the CB1 and CB2 receptors, which are expressed predominantly in the brain and immune system respectively.  Density of expression varies based on species and correlates with the efficacy that cannabinoids will have in modulating specific aspects of behavior related to the site of expression. For example, in rodents, the highest concentration of cannabinoid binding sites are in the basal ganglia and cerebellum, regions of the brain involved in the initiation and coordination of movement.  In humans, cannabinoid receptors exist in much lower concentration in these regions, which helps explain why cannabinoids possess a greater efficacy in altering rodent motor movements than they do in humans.
A recent analysis of cannabinoid binding in CB1 and CB2 receptor knockout mice found cannabinoid responsiveness even when these receptors were not being expressed, indicating that an additional binding receptor may be present in the brain.  Binding has been demonstrated by 2-arachidonoylglycerol (2-AG) on the TRPV1 receptor suggesting that this receptor may be a candidate for the established response. 
In addition to CB1 and CB2, certain orphan receptors are known to bind endocannabinoids as well, including GPR18, GPR55 (a regulator of neuroimmune function), and GPR119. CB1 has also been noted to form a functional human receptor heterodimer in orexin neurons with OX1, the CB1–OX1 receptor, which mediates feeding behavior and certain physical processes such as cannabinoid-induced pressor responses which are known to occur through signaling in the rostral ventrolateral medulla.  
Endocannabinoid synthesis, release, and degradation Edit
During neurotransmission, the pre-synaptic neuron releases neurotransmitters into the synaptic cleft which bind to cognate receptors expressed on the post-synaptic neuron. Based upon the interaction between the transmitter and receptor, neurotransmitters may trigger a variety of effects in the post-synaptic cell, such as excitation, inhibition, or the initiation of second messenger cascades. Based on the cell, these effects may result in the on-site synthesis of endogenous cannabinoids anandamide or 2-AG by a process that is not entirely clear, but results from an elevation in intracellular calcium.  Expression appears to be exclusive, so that both types of endocannabinoids are not co-synthesized. This exclusion is based on synthesis-specific channel activation: a recent study found that in the bed nucleus of the stria terminalis, calcium entry through voltage-sensitive calcium channels produced an L-type current resulting in 2-AG production, while activation of mGluR1/5 receptors triggered the synthesis of anandamide. 
Evidence suggests that the depolarization-induced influx of calcium into the post-synaptic neuron causes the activation of an enzyme called transacylase. This enzyme is suggested to catalyze the first step of endocannabinoid biosynthesis by converting phosphatidylethanolamine, a membrane-resident phospholipid, into N-acyl-phosphatidylethanolamine (NAPE). Experiments have shown that phospholipase D cleaves NAPE to yield anandamide.   This process is mediated by bile acids.   In NAPE-phospholipase D (NAPEPLD)-knockout mice, cleavage of NAPE is reduced in low calcium concentrations, but not abolished, suggesting multiple, distinct pathways are involved in anandamide synthesis.  The synthesis of 2-AG is less established and warrants further research.
Once released into the extracellular space by a putative endocannabinoid transporter, messengers are vulnerable to glial cell inactivation. Endocannabinoids are taken up by a transporter on the glial cell and degraded by fatty acid amide hydrolase (FAAH), which cleaves anandamide into arachidonic acid and ethanolamine or monoacylglycerol lipase (MAGL), and 2-AG into arachidonic acid and glycerol.  While arachidonic acid is a substrate for leukotriene and prostaglandin synthesis, it is unclear whether this degradative byproduct has unique functions in the central nervous system.   Emerging data in the field also points to FAAH being expressed in postsynaptic neurons complementary to presynaptic neurons expressing cannabinoid receptors, supporting the conclusion that it is major contributor to the clearance and inactivation of anandamide and 2-AG after endocannabinoid reuptake.  A neuropharmacological study demonstrated that an inhibitor of FAAH (URB597) selectively increases anandamide levels in the brain of rodents and primates. Such approaches could lead to the development of new drugs with analgesic, anxiolytic-like and antidepressant-like effects, which are not accompanied by overt signs of abuse liability. 
Binding and intracellular effects Edit
Cannabinoid receptors are G-protein coupled receptors located on the pre-synaptic membrane. While there have been some papers that have linked concurrent stimulation of dopamine and CB1 receptors to an acute rise in cyclic adenosine monophosphate (cAMP) production, it is generally accepted that CB1 activation via cannabinoids causes a decrease in cAMP concentration  by inhibition of adenylyl cyclase and a rise in the concentration of mitogen-activated protein kinase (MAP kinase).   The relative potency of different cannabinoids in inhibition of adenylyl cyclase correlates with their varying efficacy in behavioral assays. This inhibition of cAMP is followed by phosphorylation and subsequent activation of not only a suite of MAP kinases (p38/p42/p44), but also the PI3/PKB and MEK/ERK pathway.   Results from rat hippocampal gene chip data after acute administration of tetrahydrocannabinol (THC) showed an increase in the expression of transcripts encoding myelin basic protein, endoplasmic proteins, cytochrome oxidase, and two cell adhesion molecules: NCAM, and SC1 decreases in expression were seen in both calmodulin and ribosomal RNAs.  In addition, CB1 activation has been demonstrated to increase the activity of transcription factors like c-Fos and Krox-24. 
Binding and neuronal excitability Edit
The molecular mechanisms of CB1-mediated changes to the membrane voltage have also been studied in detail. Cannabinoids reduce calcium influx by blocking the activity of voltage-dependent N-, P/Q- and L-type calcium channels.   In addition to acting on calcium channels, activation of Gi/o and Gs, the two most commonly coupled G-proteins to cannabinoid receptors, has been shown to modulate potassium channel activity. Recent studies have found that CB1 activation specifically facilitates potassium ion flux through GIRKs, a family of potassium channels.  Immunohistochemistry experiments demonstrated that CB1 is co-localized with GIRK and Kv1.4 potassium channels, suggesting that these two may interact in physiological contexts. 
In the central nervous system, CB1 receptors influence neuronal excitability, reducing the incoming synaptic input.  This mechanism, known as presynaptic inhibition, occurs when a postsynaptic neuron releases endocannabinoids in retrograde transmission, which then bind to cannabinoid receptors on the presynaptic terminal. CB1 receptors then reduce the amount of neurotransmitter released, so that subsequent excitation in the presynaptic neuron results in diminished effects on the postsynaptic neuron. It is likely that presynaptic inhibition uses many of the same ion channel mechanisms listed above, although recent evidence has shown that CB1 receptors can also regulate neurotransmitter release by a non-ion channel mechanism, i.e. through Gi/o-mediated inhibition of adenylyl cyclase and protein kinase A.  Direct effects of CB1 receptors on membrane excitability have been reported, and strongly impact the firing of cortical neurons.  A series of behavioral experiments demonstrated that NMDAR, an ionotropic glutamate receptor, and the metabotropic glutamate receptors (mGluRs) work in concert with CB1 to induce analgesia in mice, although the mechanism underlying this effect is unclear. [ citation needed ]
Mice treated with tetrahydrocannabinol (THC) show suppression of long-term potentiation in the hippocampus, a process that is essential for the formation and storage of long-term memory.  These results may concur with anecdotal evidence suggesting that smoking cannabis impairs short-term memory.  Consistent with this finding, mice without the CB1 receptor show enhanced memory and long-term potentiation indicating that the endocannabinoid system may play a pivotal role in the extinction of old memories. One study found that the high-dose treatment of rats with the synthetic cannabinoid HU-210 over several weeks resulted in stimulation of neural growth in the rats' hippocampus region, a part of the limbic system playing a part in the formation of declarative and spatial memories, but did not investigate the effects on short-term or long-term memory.  Taken together, these findings suggest that the effects of endocannabinoids on the various brain networks involved in learning and memory may vary.
Role in hippocampal neurogenesis Edit
In the adult brain, the endocannabinoid system facilitates the neurogenesis of hippocampal granule cells.   In the subgranular zone of the dentate gyrus, multipotent neural progenitors (NP) give rise to daughter cells that, over the course of several weeks, mature into granule cells whose axons project to and synapse onto dendrites on the CA3 region.  NPs in the hippocampus have been shown to possess fatty acid amide hydrolase (FAAH) and express CB1 and utilize 2-AG.  Intriguingly, CB1 activation by endogenous or exogenous cannabinoids promote NP proliferation and differentiation this activation is absent in CB1 knockouts and abolished in the presence of antagonist.  
Induction of synaptic depression Edit
Endocannabinoids are known to influence synaptic plasticity, and are in particular thought to mediate long-term depression (LTD, which refers to neuronal firing, not psychological depression). Short-term depression (STD) has also been described (see the next paragraph). First reported in the striatum,  this system is known to function in several other brain structures such as the nucleus accumbens, amygdala, hippocampus, cerebral cortex, cerebellum, ventral tegmental area (VTA), brain stem, and superior colliculus.  Typically, these retrograde transmitters are released by the postsynaptic neuron and induce synaptic depression by activating the presynaptic CB1 receptors. 
It has further been suggested that different endocannabinoids, i.e. 2-AG and anandamide, might mediate different forms of synaptic depression through different mechanisms.  The study conducted with the bed nucleus of the stria terminalis found that the endurance of the depressant effects was mediated by two different signaling pathways based on the type of receptor activated. 2-AG was found to act on presynaptic CB1 receptors to mediate retrograde STD following activation of L-type calcium channeles, while anandamide was synthesized after mGluR5 activation and triggered autocrine signalling onto postsynapic TRPV1 receptors that induced LTD.  These findings provide the brain a direct mechanism to selectively inhibit neuronal excitability over variable time scales. By selectively internalizing different receptors, the brain may limit the production of specific endocannabinoids to favor a time scale in accordance with its needs.
Evidence for the role of the endocannabinoid system in food-seeking behavior comes from a variety of cannabinoid studies. Emerging data suggests that THC acts via CB1 receptors in the hypothalamic nuclei to directly increase appetite.  It is thought that hypothalamic neurons tonically produce endocannabinoids that work to tightly regulate hunger. The amount of endocannabinoids produced is inversely correlated with the amount of leptin in the blood.  For example, mice without leptin not only become massively obese but express abnormally high levels of hypothalamic endocannabinoids as a compensatory mechanism.  Similarly, when these mice were treated with an endocannabinoid inverse agonists, such as rimonabant, food intake was reduced.  When the CB1 receptor is knocked out in mice, these animals tend to be leaner and less hungry than wild-type mice. A related study examined the effect of THC on the hedonic (pleasure) value of food and found enhanced dopamine release in the nucleus accumbens and increased pleasure-related behavior after administration of a sucrose solution.  A related study found that endocannabinoids affect taste perception in taste cells  In taste cells, endocannabinoids were shown to selectively enhance the strength of neural signaling for sweet tastes, whereas leptin decreased the strength of this same response. While there is need for more research, these results suggest that cannabinoid activity in the hypothalamus and nucleus accumbens is related to appetitive, food-seeking behavior. 
Energy balance and metabolism Edit
The endocannabinoid system has been shown to have a homeostatic role by controlling several metabolic functions, such as energy storage and nutrient transport. It acts on peripheral tissues such as adipocytes, hepatocytes, the gastrointestinal tract, the skeletal muscles and the endocrine pancreas. It has also been implied in modulating insulin sensitivity. Through all of this, the endocannabinoid system may play a role in clinical conditions, such as obesity, diabetes, and atherosclerosis, which may also give it a cardiovascular role. 
Stress response Edit
While the secretion of glucocorticoids in response to stressful stimuli is an adaptive response necessary for an organism to respond appropriately to a stressor, persistent secretion may be harmful. The endocannabinoid system has been implicated in the habituation of the hypothalamic-pituitary-adrenal axis (HPA axis) to repeated exposure to restraint stress. Studies have demonstrated differential synthesis of anandamide and 2-AG during tonic stress. A decrease of anandamide was found along the axis that contributed to basal hypersecretion of corticosterone in contrast, an increase of 2-AG was found in the amygdala after repeated stress, which was negatively correlated to magnitude of the corticosterone response. All effects were abolished by the CB1 antagonist AM251, supporting the conclusion that these effects were cannabinoid-receptor dependent.  These findings show that anandamide and 2-AG divergently regulate the HPA axis response to stress: while habituation of the stress-induced HPA axis via 2-AG prevents excessive secretion of glucocorticoids to non-threatening stimuli, the increase of basal corticosterone secretion resulting from decreased anandamide allows for a facilitated response of the HPA axis to novel stimuli.
Exploration, social behavior, and anxiety Edit
These contrasting effects reveal the importance of the endocannabinoid system in regulating anxiety-dependent behavior. Results suggest that glutamatergic cannabinoid receptors are not only responsible for mediating aggression, but produce an anxiolytic-like function by inhibiting excessive arousal: excessive excitation produces anxiety that limited the mice from exploring both animate and inanimate objects. In contrast, GABAergic neurons appear to control an anxiogenic-like function by limiting inhibitory transmitter release. Taken together, these two sets of neurons appear to help regulate the organism's overall sense of arousal during novel situations. 
Immune system Edit
In laboratory experiments, activation of cannabinoid receptors had an effect on the activation of GTPases in macrophages, neutrophils, and bone marrow cells. These receptors have also been implicated in the migration of B cells into the marginal zone and the regulation of IgM levels. 
Female reproduction Edit
The developing embryo expresses cannabinoid receptors early in development that are responsive to anandamide secreted in the uterus. This signaling is important in regulating the timing of embryonic implantation and uterine receptivity. In mice, it has been shown that anandamide modulates the probability of implantation to the uterine wall. For example, in humans, the likelihood of miscarriage increases if uterine anandamide levels are too high or low.  These results suggest that intake of exogenous cannabinoids (e.g. cannabis) can decrease the likelihood for pregnancy for women with high anandamide levels, and alternatively, it can increase the likelihood for pregnancy in women whose anandamide levels were too low.  
Autonomic nervous system Edit
Peripheral expression of cannabinoid receptors led researchers to investigate the role of cannabinoids in the autonomic nervous system. Research found that the CB1 receptor is expressed presynaptically by motor neurons that innervate visceral organs. Cannabinoid-mediated inhibition of electric potentials results in a reduction in noradrenaline release from sympathetic nervous system nerves. Other studies have found similar effects in endocannabinoid regulation of intestinal motility, including the innervation of smooth muscles associated with the digestive, urinary, and reproductive systems. 
At the spinal cord, cannabinoids suppress noxious-stimulus-evoked responses of neurons in the dorsal horn, possibly by modulating descending noradrenaline input from the brainstem.  As many of these fibers are primarily GABAergic, cannabinoid stimulation in the spinal column results in disinhibition that should increase noradrenaline release and attenuation of noxious-stimuli-processing in the periphery and dorsal root ganglion.
The endocannabinoid most researched in pain is palmitoylethanolamide. Palmitoylethanolamide is a fatty amine related to anandamide, but saturated and although initially it was thought that palmitoylethanolamide would bind to the CB1 and the CB2 receptor, later it was found that the most important receptors are the PPAR-alpha receptor, the TRPV receptor and the GPR55 receptor. Palmitoylethanolamide has been evaluated for its analgesic actions in a great variety of pain indications  and found to be safe and effective.
Modulation of the endocannabinoid system by metabolism to N-arachidinoyl-phenolamine (AM404), an endogenous cannabinoid neurotransmitter, has been discovered to be one mechanism  for analgesia by acetaminophen (paracetamol).
Endocannabinoids are involved in placebo induced analgesia responses. 
Anandamide and N-arachidonoyl dopamine (NADA) have been shown to act on temperature-sensing TRPV1 channels, which are involved in thermoregulation.  TRPV1 is activated by the exogenous ligand capsaicin, the active component of chili peppers, which is structurally similar to endocannabinoids. NADA activates the TRPV1 channel with an EC50 of approximately of 50 nM. [ clarify ] The high potency makes it the putative endogenous TRPV1 agonist.  Anandamide has also been found to activate TRPV1 on sensory neuron terminals, and subsequently cause vasodilation.  TRPV1 may also be activated by methanandamide and arachidonyl-2'-chloroethylamide (ACEA). 
Increased endocannabinoid signaling within the central nervous system promotes sleep-inducing effects. Intercerebroventricular administration of anandamide in rats has been shown to decrease wakefulness and increase slow-wave sleep and REM sleep.  Administration of anandamide into the basal forebrain of rats has also been shown to increase levels of adenosine, which plays a role in promoting sleep and suppressing arousal.  REM sleep deprivation in rats has been demonstrated to increase CB1 receptor expression in the central nervous system.  Furthermore, anandamide levels possess a circadian rhythm in the rat, with levels being higher in the light phase of the day, which is when rats are usually asleep or less active, since they are nocturnal. 
Physical exercise Edit
Anandamide is an endogenous cannabinoid neurotransmitter that binds to cannabinoid receptors.  The ECS is also involved in mediating some of the physiological and cognitive effects of voluntary physical exercise in humans and other animals, such as contributing to exercise-induced euphoria as well as modulating locomotor activity and motivational salience for rewards.   In humans, the plasma concentration of certain endocannabinoids (i.e., anandamide) have been found to rise during physical activity   since endocannabinoids can effectively penetrate the blood–brain barrier, it has been suggested that anandamide, along with other euphoriant neurochemicals, contributes to the development of exercise-induced euphoria in humans, a state colloquially referred to as a runner's high.  
The endocannabinoid system is by molecular phylogenetic distribution of apparently ancient lipids in the plant kingdom, indicative of biosynthetic plasticity and potential physiological roles of endocannabinoid-like lipids in plants,  and detection of arachidonic acid (AA) indicates chemotaxonomic connections between monophyletic groups with common ancestor dates to around 500 million years ago (Silurian Devonian). The phylogenetic distribution of these lipids may be a consequence of interactions/adaptations to the surrounding conditions such as chemical plant-pollinator interactions, communication and defense mechanisms. The two novel EC-like molecules derived from the eicosatetraenoic acid juniperonic acid, an omega-3 structural isomer of AA, namely juniperoyl ethanolamide and 2-juniperoyl glycerol (1/2-AG) in gymnosperms, lycophytes and few monilophytes, show AA is an evolutionarily conserved signalling molecule that acts in plants in response to stress similar to that in animal systems. 
COVID-19 alters gray matter volume in the brain, new study shows
Covid-19 patients who receive oxygen therapy or experience fever show reduced gray matter volume in the frontal-temporal network of the brain, according to a new study led by researchers at Georgia State University and the Georgia Institute of Technology.
The study found lower gray matter volume in this brain region was associated with a higher level of disability among Covid-19 patients, even six months after hospital discharge.
Gray matter is vital for processing information in the brain and gray matter abnormality may affect how well neurons function and communicate. The study, published in the May 2021 issue of Neurobiology of Stress, indicates gray matter in the frontal network could represent a core region for brain involvement in Covid-19, even beyond damage related to clinical manifestations of the disease, such as stroke.
The researchers, who are affiliated with the Center for Translational Research in Neuroimaging and Data Science (TReNDS), analyzed computed tomography scans in 120 neurological patients, including 58 with acute Covid-19 and 62 without Covid-19, matched for age, gender and disease. They used source-based morphometry analysis, which boosts the statistical power for studies with a moderate sample size.
"Science has shown that the brain's structure affects its function, and abnormal brain imaging has emerged as a major feature of Covid?19," said Kuaikuai Duan, the study's first author, a graduate research assistant at TReNDS and Ph.D. student in Georgia Tech's School of Electrical and Computer Engineering. "Previous studies have examined how the brain is affected by Covid-19 using a univariate approach, but ours is the first to use a multivariate, data-driven approach to link these changes to specific Covid-19 characteristics (for example fever and lack of oxygen) and outcome (disability level)."
The analysis showed patients with higher levels of disability had lower gray matter volume in the superior, medial and middle frontal gyri at discharge and six months later, even when controlling for cerebrovascular diseases. Gray matter volume in this region was also significantly reduced in patients receiving oxygen therapy compared to patients not receiving oxygen therapy. Patients with fever had a significant reduction in gray matter volume in the inferior and middle temporal gyri and the fusiform gyrus compared to patients without fever. The results suggest Covid-19 may affect the frontal-temporal network through fever or lack of oxygen.
Reduced gray matter in the superior, medial and middle frontal gyri was also present in patients with agitation compared to patients without agitation. This implies that gray matter changes in the frontal region of the brain may underlie the mood disturbances commonly exhibited by Covid-19 patients.
"Neurological complications are increasingly documented for patients with Covid-19," said Vince Calhoun, senior author of the study and director of TReNDS. Calhoun is Distinguished University Professor of Psychology at Georgia State and holds appointments in the School of Electrical and Computer Engineering at Georgia Tech and in neurology and psychiatry at Emory University. "A reduction of gray matter has also been shown to be present in other mood disorders such as schizophrenia and is likely related to the way that gray matter influences neuron function."
The study's findings demonstrate changes to the frontal-temporal network could be used as a biomarker to determine the likely prognosis of Covid-19 or evaluate treatment options for the disease. Next, the researchers hope to replicate the study on a larger sample size that includes many types of brain scans and different populations of Covid-19 patients.
TReNDS is a partnership among Georgia State, Georgia Tech and Emory University and is focused on improving our understanding of the human brain using advanced analytic approaches. The center uses large-scale data sharing and multi-modal data fusion techniques, including deep learning, genomics, brain mapping and artificial intelligence.
Covid 21 is coming – the second half of a binary weapons system.
(Natural News) About a year ago, I gave a live presentation in Branson, Missouri, that is only now being made fully public. The presentation, shown below via Brighteon.com, reveals that the real master plan which led to COVID is actually an extermination plan for humanity.
Population reduction has been the goal all along. But where the globalists have shown their true evil genius is in their choice of creating a biological weapon with high transmission rather than high fatality rates. The virus was never very deadly to people under the age of 50, but it was always highly contagious to people of all ages. And that contagiousness, it turns out, was enough to advance their nefarious plan against humanity.
The rapid spread of the virus allowed the globalist-controlled media to claim “cases” were skyrocketing, thereby justifying weaponized lockdowns and a global rolling out of medical fascism disguised as “public health” policies. Based entirely on the speed of the spread of the virus, cities, states and nations of the world were able to achieve three key goals that represent the necessary precursors to global human extermination:
- Crushing the existing human economies of the world, including food production, ultimately leading to mass famine, homelessness and total dependence on government.
- Rolling out new, Orwellian medical fascism laws and edicts that set the precedent for mass arrests and forced relocation into “quarantine camps” for those who resist. These camps, of course, are actually death camps and processing facilities for eliminating human beings.
- Forcing compliance with global vaccine mandates which will of course be used to achieve global infertility and accelerated deaths from diseases and subsequent infections. Whereas a pathogen could not achieve a 90% death rate on its own, the engineered pathogen (the Wuhan coronavirus) was able to be used to drive people into mass vaccine compliance, during which they can be directly injected with toxic substances, vaccine compliance tracking nanotech (quantum dots) and biology-altering mRNA sequences that literally hijack the body’s cells and reprogram them to produce whatever protein sequences are engineered into the mRNA vaccines.
Thus, globalists have simultaneously built a global pandemic prison camp combined with a mandatory vaccine obedience system through which they can repeatedly spread more infectious disease and promote accelerated deaths or infertility.
The end goal, as globalists like Bill Gates openly support, is the elimination of billions of human beings living today. Ideally, globalists seek to reduce the world population to about 500 million people, which is roughly a 94% reduction in the current human population.
The world you once knew is never coming back, because the globalists who run the world have other plans
Each day, more and more people are coming to realize that there will be no restoration of the world we all once knew. Globalists have no intention of restoring human freedom, economic prosperity and global mobility. Now, human societies are being deliberately crushed — even in the face of contradictory scientific evidence that shows lockdowns don’t work — in order to cause mass destitution and collapse.
Only through this planned collapse can the billions of people in the world be forced into subservience to the globalist depopulation agenda.
A key element of this is the Universal Basic Income (UBI), which has already been rolled out across America for the last several months, under the approval of Republicans, Democrats and President Trump. The UBI provides basic sustenance income to allow people to purchase food and stay alive, while CDC mandates prohibit the eviction of renters who can no longer pay rent. Through the UBI, the eviction ban and the pumping up of the stock market with Fed money printing policies, America remains under the false appearance that the economy is rebounding. In truth, these are all temporary, makeshift tactics to prevent millions of homeless from spilling out into the streets right before an election.
The real plan — about to be rolled out — is to tie UBI benefits to vaccine compliance and speech compliance. Only the obedient will be granted government credits for food, and anyone who refuses to take the new vaccine will be cut off from government benefits. This is a deliberate “squeeze” to force the sheeple into mass vaccine suicide by making sure they cannot function in society (or receive government benefits) unless they go along with the vaccine mandates, which are of course a global extermination program disguised as a public health program.
How vaccines will be used to exterminate billions of humans while amplifying infectious disease on a global scale
The mass extermination via vaccines consists of two strategies:
- Lacing the vaccines with new bioweapons viral strains to ensure the continuation of the “outbreak” narrative. Notably, this only requires less than one percent of administered vaccines to be laced.
- Engineering the vaccines to cause a very high fatality rate upon exposure to a secondary future infection, in a fatal reaction called a “cytokine storm,” which is a hyper-inflammation event that leads to rapid death.
Thus, people won’t be dropping dead right away after taking the vaccines. Instead, they will seem fine until the next major bioweapon pandemic hits them, at which point the fatality rate will be extremely high (perhaps as high as 75% averaged across all age groups).
The next strain to be released via the vaccines will be COVID-21, and the COVID-21 strain could be rightly considered the second half of a binary weapon system that will achieve extremely high kill rates for human beings across the globe.
Importantly, the mass die-offs will further justify government lockdowns, quarantines and medical authoritarianism that grants governments the power to forcefully inject people, kidnap people, imprison people and even exterminate people at will. The mass hysteria from the sudden wave of deaths will also feed directly into the justification of increased censorship by the tech giants, which will de-platform anyone who discusses the truth about how this entire scheme was planned from the start.
What ends up being created is a feedback loop of death, hysteria and tyranny. The more people die, the more hysteria the media spreads and the more tyranny is justified by the state. This, in turn, results in higher numbers of vaccine injections, which spread more weaponized viral strains, resulting in another wave of hysteria and so on. It’s the perfect scam of tyranny and depopulation: The very governments who are building the bioweapons are using them to exterminate the masses while using the infections to justify their own power to administer the extermination weapons (i.e. vaccines).
Government tyrants are giggling with joy with their newfound powers over life and death
YouTube has just recently confirmed it will ban all vaccine videos that don’t toe the line of Big Pharma and the China-run WHO. We’ve all witnessed the accelerating purges of so-called “anti-vax” channels and speakers across all the major tech platforms. It’s all part of the narrative control that will maintain information monopolies to keep pushing the vaccines, lockdowns and tyranny that’s killing human beings by the billions.
This is how they pull it off! It’s not the pandemic that’s really killing people it’s the governments. And any who don’t surrender to the tyranny will be singled out as “threats” to public health, then silenced or forcibly removed.
Victoria, Australia has already beta tested these programs and has found a shocking degree of compliance among the population that’s targeted for extermination. New Zealand has also discovered shockingly high levels of compliance, and Canada is finding much the same thing. As it turns out, “progressive” societies are filled with eager-to-obey sheeple who maintain irrational faith and trust in government — the very same government that’s preparing them all to be terminated.
Resistance groups are growing all around the world, including in America where local economies (in conservative states) have fared relatively well by avoiding the punitive lockdowns that now characterize left-leaning cities and states.
This is the reason the globalists are working desperately to remove President Trump from power: Trump and his followers are the last remaining defenses for humanity, standing up against the anti-human forces of tyranny and destruction that built the coronavirus bioweapon in the first place (and released it on purpose, then lied about it). Thus, Trump must be removed from power at all costs, and his followers and supporters must be silenced, criminalized, smeared and eliminated at all costs as well. No pro-human voice that resists the COVID-21 tyranny scheme may be allowed to exist, or the entire plan could be placed in jeopardy because it requires broad voluntary compliance of the sheeple who are being culled. The minute the sheeple wake up and realize they are being led to the slaughter, they might not follow orders so easily.
How billions of humans will line up and beg to be “suicided” with vaccines
Rational people can process most of what I’ve described above, if they do the research and aren’t brain damaged from fluoride, pesticides, heavy metals and 5G. But now we bring in a topic where many people just can’t fathom the reality: Earth’s globalists are following orders from non-human entities.
Different people describe these non-human, non-Earth entities in different ways. To some people, they are demons of supernatural origin. To others, they are aliens of extraterrestrial origin. Still others say they are AI systems from advanced civilizations across the cosmos, and another explanation describes these influencing entities as interdimensional beings from a parallel universe. (Interesting note: CERN scientists have announced they are preparing to power up CERN to literally “make contact with a parallel universe,” according to mainstream media headlines.)
A defense of the binary in human sex
As a biologist, I get especially irked at the repeated claim that sex in humans is “a spectrum, not a binary.” In fact, as I’ve discussed several times before (e.g., here, here, here and here), sex might as well be a binary, because the overwhelming majority of people conform to the definitions of either male or female, which involve differential gamete production (sperm vs. eggs), and only slightly fewer fail to conform to a binary of other primary sexual characteristics (appearance of genitalia) or secondary sexual characteristics that appear at puberty (breasts, pubic hair, etc.).
To be a bit more precise, biological sex in humans is bimodal: if you do a frequency plot with “sex” on the X axis and “frequency of individuals conforming to that sex” on the Y axis, you get a huge peak at “male”, another huge peak at “female”, and then a few tiny blips in between that conform to hermaphrodites or intersexes.
There’s a reason why sex is a binary: evolution produces two distinct sexes who mate with each other to produce offspring. Exactly why there is sex rather than all of us budding off clones or reproducing in other asexual ways is an unsolved problem, but once there is sexual reproduction, you can construct a reasonable theory about why there should be two of them, and that they should be distinct. (A few species have “mating types” that encompass more “sexes”, but these are virtually nonexistent in vertebrates.)
Gender, on the other hand, is less bimodal, for it’s based on people’s claims of what they are, and there are lots of different socio-sexual roles that people can claim. Still, gender is also bimodal, though less binary, for the vast majority of people still claim identities of “male” and “female”. But let’s leave that aside, as today we’re dealing with biological sex.
And it’s especially galling that biologists, of all people—even evolutionary biologists, who should know better—will assert that sex is not a binary. I was appalled, for instance, when the Society for the Study of Evolution (SSE), of which I used to be President, issued a woke-ish statement that neither sex nor gender were binary (see link below). That’s misleading for both terms, but especially for sex. Do they not know the evolutionary rationale for having distinct and separate sexes? (Answer: yes they do, but they’re trying to be woke.)
The shameful part of all this is that the scientific journal Nature, as well as three evolutionary biology/ecology societies, who should know better, made statements or editorials that neither sex nor gender are binary. That’s a flat-out abnegation of both their responsibility and of science itself. Evolution itself produces a binary of sex! To be anthropomorphic, evolution wants a binary of sex.
A while back, biologists like me were voices crying in the wilderness, for if you say that sex is a binary, you’re liable to be labeled a transphobe. (That’s a foolish slur, for the facts about nature are independent of how we should treat transsexual or other “nonconforming” individuals.)
But now other biologists are speaking up. Two of them, Colin Wright and Emma Hilton, have a sensible column about the sex binary in yesterday’s Wall Street Journal (a conservative organ, of course: you’ll never see a claim for a sex binary in Salon or HuffPost, much less the New York Times, which ran an op-ed by Anne Fausto-Sterling denying that sex was binary).
Colin Wright is a research fellow at Penn State, and Emma Hilton a developmental biologist and research fellow at the University of Manchester. You can see the beginning of their WSJ article by clicking on the link below, but it’s paywalled. A judicious inquiry might, however, yield you a copy:
Wright and Hilton not only give examples of the mainstream press denying that sex is a binary, but explain why that denial is wrong, and then briefly discuss the danger of this kind of misinformation. (Yes, the claim that sex in humans is not a binary is pretty much a lie, and is made on ideological rather than scientific grounds.) I’ve indented some quotes from their short but perspicacious piece:
Yet it’s one thing to claim that a man can “identify” as a woman or vice versa. Increasingly we see a dangerous and antiscientific trend toward the outright denial of biological sex.
“The idea of two sexes is simplistic,” an article in the scientific journal Nature declared in 2015. “Biologists now think there is a wider spectrum than that.” A 2018 Scientific American piece asserted that “biologists now think there is a larger spectrum than just binary female and male.” And an October 2018 New York Times headline promised to explain “Why Sex Is Not Binary.”
The argument is that because some people are intersex — they have developmental conditions resulting in ambiguous sex characteristics — the categories male and female exist on a “spectrum,” and are therefore no more than “social constructs.” If male and female are merely arbitrary groupings, it follows that everyone, regardless of genetics or anatomy should be free to choose to identify as male or female, or to reject sex entirely in favor of a new bespoke “gender identity.
To characterize this line of reasoning as having no basis in reality would be an egregious understatement. It is false at every conceivable scale of resolution.
Why sex is strongly bimodal, and for all practical purposes is a binary in humans. Here they’re talking about the rare exceptions for sex, not gender:
There is a difference, however, between the statements that there are only two sexes (true) and that everyone can be neatly categorized as either male or female (false). The existence of only two sexes does not mean sex is never ambiguous. But intersex individuals are extremely rare, and they are neither a third sex nor proof that sex is a “spectrum” or a “social construct.” Not everyone needs to be discretely assignable to one or the other sex in order for biological sex to be functionally binary. To assume otherwise — to confuse secondary sexual traits with biological sex itself — is a category error.
Finally, they argue that it’s important for society to recognize the bimodality of sex (again, we’re not talking about gender). There are a number of issues, and remember this is their list, not mine, though I’ve emphasized the effect on sports rather than the more important issues they mention here:
Denying the reality of biological sex and supplanting it with subjective “gender identity” is not merely an eccentric academic theory. It raises serious human-rights concerns for vulnerable groups including women, homosexuals and children.
Women have fought hard for sex-based legal protections. Female-only spaces are necessary due to the pervasive threat of male violence and sexual assault. Separate sporting categories are also necessary to ensure that women and girls don’t have to face competitors who have acquired the irreversible performance-enhancing effects conferred by male puberty. The different reproductive roles of males and females require laws to safeguard women from discrimination in the workplace and elsewhere. The falsehood that sex is rooted in subjective identity instead of objective biology renders all these sex-based rights impossible to enforce.
They posit an effect on children, too, and this is something I’ve thought of when I see parents hailed as heroes for immediately accepting that their children—children as young as two or three—are transgender, as they claim. Wright and Hilton posit that the blurring of sex categories in the popular literature may lead parents to contribute to confusion in their children and, on what seems to be a one-way express, ineluctably lead to their irrevocable identification as transgender kids, and then to hormone treatment and surgery. The number of these children has increased exponentially in recent years could this be correlated with the increasing number of claims that sex is merely a social construct? Wright and Hilton think so, and their point shouldn’t be dismissed:
Those most vulnerable to sex denialism are children. When they’re taught that sex is grounded in identity instead of biology, sex categories can easily become conflated with regressive stereotypes of masculinity and femininity. Masculine girls and feminine boys may become confused about their own sex. The dramatic rise of “gender dysphoric” adolescents — especially young girls — in clinics likely reflects this new cultural confusion.
The large majority of gender-dysphoric youths eventually outgrow their feelings of dysphoria during puberty, and many end up identifying as homosexual adults. “Affirmation” therapies, which insist a child’s cross-sex identity should never be questioned, and puberty-blocking drugs, advertised as a way for children to “buy time” to sort out their identities, may only solidify feelings of dysphoria, setting them on a pathway to more invasive medical interventions and permanent infertility. This pathologizing of sex-atypical behavior is extremely worrying and regressive. It is similar to gay “conversion” therapy, except that it’s now bodies instead of minds that are being converted to bring children into “proper” alignment with themselves.
They (and I) are not of course denying that gender-dysphoric children should be treated with compassion and, if their dysphoria persists into young adulthood, begin talking about medical interventions. (I still feel this needs to wait until the mid-teen years, when children become adults and can make such decisions.) But regardless of what we do, it’s time for biologists to not only recognize the truth, but proclaim it loudly to those obfuscating scientist-ideologues who claim that sex is not a binary. And that’s the way Wright and Hilton end their piece:
The time for politeness on this issue has passed. Biologists and medical professionals need to stand up for the empirical reality of biological sex. When authoritative scientific institutions ignore or deny empirical fact in the name of social accommodation, it is an egregious betrayal to the scientific community they represent. It undermines public trust in science, and it is dangerously harmful to those most vulnerable.
A new partnership for humanity
We’re at an interesting transition point where we are moving from using our tools as passive extensions of ourselves, to working with them as active partners. An axe or a hammer is a passive extension of a hand, but a drone forms a distributed intelligence along with its operator, and is closer to a dog or horse than a device. Such tools can interact with us in ways never before possible, such as working with us in a choreographed dance for a talent competition or helping us script a novel or new sci-fi movie.
Our tools are now actors unto themselves, and their future is in our hands. Think about the evolution of the car: from horse and carriage to Model-T, from cruise control to adaptive cruise control, and now to driverless cars.
Engineers are now programming cars using subtle ethics models to determine, in situations where an accident is unavoidable, whether to hit pedestrians or veer off the road and jeopardize the driver’s life.
The conclusions such cars reach in real situations might well be very different from the decisions you or I might make if we were in the driver’s seat, but with hindsight we might judge them to be much better, even if they initially seem alien to us. Ideally, such technologically evolved decision-making abilities can flourish alongside evolving HI, to rethink assumptions, reframe possibilities and explore new territories.
We’ve already seen chess evolve to a new kind of game where young champions like Magnus Carlsen have adopted styles of play that take advantage of AI chess engines. With early examples of unenhanced humans and drones dancing together, it is already obvious that humans and AIs will be able to form a dizzying variety of combinations to create new kinds of art, science, wealth and meaning. What could we do if the humans in the picture were enhanced in powerful ways? What might happen if every human had perfect memory, for instance?
In short, we are poised for an explosive, generative epoch of massively increased human capability through a Cambrian explosion of possibilities represented by the simple equation: HI+AI. When HI combines with AI, we will have the most significant advancement to our capabilities of thought, creativity and intelligence that we will have ever had in history.
While we’re starting with HI+AI in health diagnosis, transportation coordination, art and music, our partnership is rapidly extending into co-creation of technology, governance and relationships, and everywhere else our HI+AI imagination takes us.
The biggest bottleneck in opening up this powerful new future is that we humans are currently highly limited in how we can participate in these possibilities. Our connection with our new creations of intelligence is limited by screens, keyboards, gestural interfaces and voice commands — constrained input/output modalities. We have very little access to our own brains, limiting our ability to co-evolve with silicon-based machines in powerful ways.
Relative to the ease and speed with which we can make progress on the development of AI, HI, speaking solely of our native biological abilities, is currently a landlocked island of intelligence potential. Unlocking the untapped capabilities of the human brain, and connecting them to these new capabilities, is the greatest challenge and opportunity today.
The single most powerful avenue for achieving this unlocking today is neuroprosthetics. In recent years, research labs around the world have made enormous strides in understanding how the brain works, how to connect it to outside sources and how we might tap more deeply into its potential. The most immediate need for these devices is apparent in the growing number of people living longer lives while suffering from neurodegenerative disorders. These devices — by directly extending HI, including our memory and other cognitive capabilities — could lead to unprecedented longevity of the mind and body. (Full disclosure: I’ve started a company in this arena.)
There are other paths to improved HI including genomics and pharmacological interventions. But these have one severe limitation, their inability to extend the brain’s ability to communicate with our tools of intelligence (AI).
To truly realize the potential of HI+AI, we need to increase the capacity of people to take in, process and use information, by orders of magnitude. For this, neuroprosthetics are the most promising avenue to meet this challenge.
Effects of Aging on the Nervous System
Brain function varies normally as people pass from childhood through adulthood to old age. During childhood, the ability to think and reason steadily increases, enabling a child to learn increasingly complex skills.
During most of adulthood, brain function is relatively stable.
After a certain age, which varies from person to person, brain function declines. Some areas of the brain decrease in size by up to 1% per year in some people but without any loss of function. Thus, age-related changes in brain structure do not always result in loss of brain function. However, a decrease in brain function with aging may be the result of numerous factors that include changes in brain chemicals (neurotransmitters),changes in nerve cells themselves, toxic substances that accumulate in the brain over time, and inherited changes. Different aspects of brain function may be affected at different times:
Short-term memory and the ability to learn new material tend to be affected relatively early.
Verbal abilities, including vocabulary and word usage, may begin to decline later.
Intellectual performance—the ability to process information (regardless of speed)—is usually maintained if no underlying neurologic or vascular disorders are present.
Reaction time and performance of tasks may become slower because the brain processes nerve impulses more slowly.
However, the effects of aging on brain function may be difficult to separate from the effects of various disorders that are common among older people. These disorders include depression, stroke, an underactive thyroid gland (hypothyroidism), and degenerative brain disorders such as Alzheimer disease.
As people age, the number of nerve cells in the brain may decrease, although the number lost varies greatly from person to person, depending on the person’s health. In addition, some types of memory are more vulnerable to loss, such as memory that holds information temporarily. However, the brain has certain characteristics that help compensate for these losses.
Redundancy: The brain has more cells than it needs to function normally. Redundancy may help compensate for the loss of nerve cells that occurs with aging and disease.
Formation of new connections: The brain actively compensates for the age-related decrease in nerve cells by making new connections between the remaining nerve cells.
Production of new nerve cells: Some areas of the brain may produce new nerve cells, especially after a brain injury or a stroke. These areas include the hippocampus (which is involved in the formation and retrieval of memories) and the basal ganglia (which coordinate and smooth out movements).
Thus, people who have had a brain injury or stroke can sometimes learn new skills, as occurs during occupational therapy.
People can influence how quickly brain function declines. For example, physical exercise seems to slow the loss of nerve cells in areas of the brain involved in memory. Such exercise also helps keep the remaining nerve cells functioning. On the other hand, consuming two or more drinks of alcohol a day can speed the decline in brain function.
As people age, blood flow to the brain may decrease by an average of 20%. The decrease in blood flow is greater in people who have atherosclerosis of the arteries to the brain (cerebrovascular disease). This disease is more likely to occur in people who have smoked for a long time or who have high blood pressure, high cholesterol, or high blood sugar (diabetes mellitus) that is not controlled by lifestyle changes or drugs. These people may lose brain cells prematurely, possibly impairing mental function. As a result, the risk of damage to blood vessels leading to vascular dementia at a relatively young age is increased.
Did You Know.
Physical exercise may slow the age-related decline in brain function.
Having uncontrolled high blood pressure, diabetes, or high cholesterol levels can speed the age-related decline in brain function.
Both IB Biology SL and HL consist of the same core requirements (95 hours). Both classes cover the same six topics in the order listed below with the same subtopics listed below:
Topic 1: Cell Biology—15 Hours for Both SL and HL
- According to the cell theory, living organisms are composed of cells.
- Organisms consisting of only one cell carry out all functions of life in that cell.
- Surface area to volume ratio is important in the limitation of cell size.
- Multicellular organisms have properties that emerge from the interaction of their cellular components.
- Specialized tissues can develop by cell differentiation in multicellular organisms.
- Differentiation involves the expression of some genes and not others in a cell's genome.
- The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses.
- Prokaryotes have a simple cell structure without compartmentalization.
- Eukaryotes have a compartmentalized cell structure.
- Electron microscopes have a much higher resolution than light microscopes.
- Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.
- Membrane proteins are diverse in terms of structure, position in the membrane and function.
- Cholesterol is a component of animal cell membranes.
- Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport.
- The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. Vesicles move materials within cells.
- Cells can only be formed by division of pre-existing cells.
- The first cells must have arisen from non-living material.
- The origin of eukaryotic cells can be explained by the endosymbiotic theory.
- Mitosis is division of the nucleus into two genetically identical daughter nuclei.
- Chromosomes condense by supercoiling during mitosis.
- Cytokinesis occurs after mitosis and is different in plant and animal cells.
- Interphase is a very active phase of the cell cycle with many processes occurring in the nucleus and cytoplasm.
- Cyclins are involved in the control of the cell cycle.
- Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours.
Topic 2: Molecular Biology—21 Hours for Both SL and HL
- Molecular biology explains living processes in terms of the chemical substances involved.
- Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist.
- Life is based on carbon compounds including carbohydrates, lipids, proteins and nucleic acids.
- Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism.
- Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions.
- Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers.
- Water molecules are polar and hydrogen bonds form between them.
- Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water.
- Substances can be hydrophilic or hydrophobic.
- Monosaccharide monomers are linked together by condensation reactions to form disaccharides and polysaccharide polymers.
- Fatty acids can be saturated, monounsaturated or polyunsaturated.
- Unsaturated fatty acids can be cis or trans isomers.
- Triglycerides are formed by condensation from three fatty acids and one glycerol.
- Amino acids are linked together by condensation to form polypeptides.
- There are 20 different amino acids in polypeptides synthesized on ribosomes.
- Amino acids can be linked together in any sequence giving a huge range of possible polypeptides.
- The amino acid sequence of polypeptides is coded for by genes.
- A protein may consist of a single polypeptide or more than one polypeptide linked together.
- The amino acid sequence determines the three-dimensional conformation of a protein.
- Living organisms synthesize many different proteins with a wide range of functions.
- Every individual has a unique proteome.
- Enzymes have an active site to which specific substrates bind.
- Enzyme catalysis involves molecular motion and the collision of substrates with the active site.
- Temperature, pH and substrate concentration affect the rate of activity of enzymes.
- Enzymes can be denatured.
- Immobilized enzymes are widely used in industry.
- The nucleic acids DNA and RNA are polymers of nucleotides.
- DNA differs from RNA in the number of strands present, the base composition and the type of pentose.
- DNA is a double helix made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs.
- The replication of DNA is semi-conservative and depends on complementary base pairing.
- Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds.
- DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template.
- Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
- Translation is the synthesis of polypeptides on ribosomes.
- The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
- Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
- Translation depends on complementary base pairing between codons on mRNA and anticodons on tRNA.
- Cell respiration is the controlled release of energy from organic compounds to produce ATP.
- ATP from cell respiration is immediately available as a source of energy in the cell.
- Anaerobic cell respiration gives a small yield of ATP from glucose.
- Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose.
- Photosynthesis is the production of carbon compounds in cells using light energy.
- Visible light has a range of wavelengths with violet the shortest wavelength and red the longest.
- Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colours.
- Oxygen is produced in photosynthesis from the photolysis of water.
- Energy is needed to produce carbohydrates and other carbon compounds from carbon dioxide.
- Temperature, light intensity and carbon dioxide concentration are possible limiting factors on the rate of photosynthesis.
Topic 3: Genetics—15 Hours for Both SL and HL
- A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic.
- A gene occupies a specific position on a chromosome.
- The various specific forms of a gene are alleles.
- Alleles differ from each other by one or only a few bases.
- New alleles are formed by mutation.
- The genome is the whole of the genetic information of an organism.
- The entire base sequence of human genes was sequenced in the Human Genome Project.
- Prokaryotes have one chromosome consisting of a circular DNA molecule.
- Some prokaryotes also have plasmids but eukaryotes do not.
- Eukaryote chromosomes are linear DNA molecules associated with histone proteins.
- In a eukaryote species there are different chromosomes that carry different genes.
- Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles of those genes.
- Diploid nuclei have pairs of homologous chromosomes.
- Haploid nuclei have one chromosome of each pair.
- One diploid nucleus divides by meiosis to produce four haploid nuclei.
- The halving of the chromosome number allows a sexual life cycle with fusion of gametes.
- DNA is replicated before meiosis so that all chromosomes consist of two sister chromatids.
- The early stages of meiosis involve pairing of homologous chromosomes and crossing over followed by condensation.
- Orientation of pairs of homologous chromosomes prior to separation is random.
- Separation of pairs of homologous chromosomes in the first division of meiosis halves the chromosome number.
- Crossing over and random orientation promotes genetic variation.
- Fusion of gametes from different parents promotes genetic variation.
- Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.
- Gametes are haploid so contain only one allele of each gene.
- The two alleles of each gene separate into different haploid daughter nuclei during meiosis.
- Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.
- Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.
- Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles.
- Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.
- Many genetic diseases have been identified in humans but most are very rare.
- Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.
- Gel electrophoresis is used to separate proteins or fragments of DNA according to size.
- PCR can be used to amplify small amounts of DNA.
- DNA profiling involves comparison of DNA.
- Genetic modification is carried out by gene transfer between species.
- Clones are groups of genetically identical organisms, derived from a single original parent cell.
- Many plant species and some animal species have natural methods of cloning.
- Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.
- Methods have been developed for cloning adult animals using differentiated cells.
Topic 4: Ecology—12 Hours for Both SL and HL
- Species are groups of organisms that can potentially interbreed to produce fertile offspring.
- Members of a species may be reproductively isolated in separate populations.
- Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods).
- Consumers are heterotrophs that feed on living organisms by ingestion.
- Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
- Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.
- A community is formed by populations of different species living together and interacting with each other.
- A community forms an ecosystem by its interactions with the abiotic environment.
- Autotrophs obtain inorganic nutrients from the abiotic environment.
- The supply of inorganic nutrients is maintained by nutrient cycling.
- Ecosystems have the potential to be sustainable over long periods of time.
- Most ecosystems rely on a supply of energy from sunlight.
- Light energy is converted to chemical energy in carbon compounds by photosynthesis.
- Chemical energy in carbon compounds flows through food chains by means of feeding.
- Energy released from carbon compounds by respiration is used in living organisms and converted to heat.
- Living organisms cannot convert heat to other forms of energy.
- Heat is lost from ecosystems.
- Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds.
- In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen carbonate ions.
- Carbon dioxide diffuses from the atmosphere or water into autotrophs.
- Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere.
- Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground.
- Methane is oxidized to carbon dioxide and water in the atmosphere.
- Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.
- Partially decomposed organic matter from past geological eras was converted either into coal or into oil and gas that accumulate in porous rocks.
- Carbon dioxide is produced by the combustion of biomass and fossilized organic matter.
- Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilized in limestone.
- Carbon dioxide and water vapour are the most significant greenhouse gases.
- Other gases including methane and nitrogen oxides have less impact.
- The impact of a gas depends on its ability to absorb long wave radiation as well as on its concentration in the atmosphere.
- The warmed Earth emits longer wavelength radiation (heat).
- Longer wave radiation is absorbed by greenhouse gases that retain the heat in the atmosphere.
- Global temperatures and climate patterns are influenced by concentrations of greenhouse gases.
- There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution 200 years ago and average global temperatures.
- Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilized organic matter.
Topic 5: Evolution and Biodiversity—12 Hours for Both SL and HL
- Evolution occurs when heritable characteristics of a species change.
- The fossil record provides evidence for evolution.
- Selective breeding of domesticated animals shows that artificial selection can cause evolution.
- Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.
- Populations of a species can gradually diverge into separate species by evolution.
- Continuous variation across the geographical range of related populations matches the concept of gradual divergence.
- Natural selection can only occur if there is variation among members of the same species.
- Mutation, meiosis and sexual reproduction cause variation between individuals in a species.
- Adaptations are characteristics that make an individual suited to its environment and way of life.
- Species tend to produce more offspring than the environment can support.
- Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.
- Individuals that reproduce pass on characteristics to their offspring.
- Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.
- The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.
- When species are discovered they are given scientific names using the binomial system.
- Taxonomists classify species using a hierarchy of taxa.
- All organisms are classified into three domains.
- The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species.
- In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species.
- Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.
- Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.
- A clade is a group of organisms that have evolved from a common ancestor.
- Evidence for which species are part of a clade can be obtained from the base sequences of a gene or the corresponding amino acid sequence of a protein.
- Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor.
- Traits can be analogous or homologous.
- Cladograms are tree diagrams that show the most probable sequence of divergence in clades.
- Evidence from cladistics has shown that classifications of some groups based on structure did not correspond with the evolutionary origins of a group or species.
Topic 6: Human Physiology—20 Hours for Both SL and HL
- The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.
- The pancreas secretes enzymes into the lumen of the small intestine.
- Enzymes digest most macromolecules in food into monomers in the small intestine.
- Villi increase the surface area of epithelium over which absorption is carried out.
- Villi absorb monomers formed by digestion as well as mineral ions and vitamins.
- Different methods of membrane transport are required to absorb different nutrients.
- Arteries convey blood at high pressure from the ventricles to the tissues of the body.
- Arteries have muscle cells and elastic fibres in their walls.
- The muscle and elastic fibres assist in maintaining blood pressure between pump cycles.
- Blood flows through tissues in capillaries. Capillaries have permeable walls that allow exchange of materials between cells in the tissue and the blood in the capillary.
- Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart.
- Valves in veins and the heart ensure circulation of blood by preventing backflow.
- There is a separate circulation for the lungs.
- The heart beat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node.
- The sinoatrial node acts as a pacemaker.
- The sinoatrial node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles.
- The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain.
- Epinephrine increases the heart rate to prepare for vigorous physical activity.
- The skin and mucous membranes form a primary defense against pathogens that cause infectious disease.
- Cuts in the skin are sealed by blood clotting.
- Clotting factors are released from platelets.
- The cascade results in the rapid conversion of fibrinogen to fibrin by thrombin.
- Ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases.
- Production of antibodies by lymphocytes in response to particular pathogens gives specific immunity.
- Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells.
- Viruses lack a metabolism and cannot therefore be treated with antibiotics. Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have multiple resistance.
- Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.
- Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange.
- Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.
- Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles.
- Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.
- Different muscles are required for inspiration and expiration because muscles only do work when they contract.
- Neurons transmit electrical impulses.
- The myelination of nerve fibres allows for saltatory conduction.
- Neurons pump sodium and potassium ions across their membranes to generate a resting potential.
- An action potential consists of depolarization and repolarization of the neuron.
- Nerve impulses are action potentials propagated along the axons of neurons.
- Propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential.
- Synapses are junctions between neurons and between neurons and receptor or effector cells.
- When presynaptic neurons are depolarized they release a neurotransmitter into the synapse.
- A nerve impulse is only initiated if the threshold potential is reached.
- Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration.
- Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.
- Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.
- Melatonin is secreted by the pineal gland to control circadian rhythms.
- A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone.
- Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.
- Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty.
- The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.
Neuroscience For Kids
Throughout history, people have compared the brain to different inventions. In the past, the brain has been said to be like a water clock and a telephone switchboard. These days, the favorite invention that the brain is compared to is a computer. Some people use this comparison to say that the computer is better than the brain some people say that the comparison shows that the brain is better than the computer. Perhaps, it is best to say that the brain is better at doing some jobs and the computer is better at doing other jobs.
Let's see how the brain and the computer are similar and different.
The Brain vs. The Computer: Similarities and Differences
Both use electrical signals to send messages.
The brain uses chemicals to transmit information the computer uses electricity. Even though electrical signals travel at high speeds in the nervous system, they travel even faster through the wires in a computer.
Both transmit information.
A computer uses switches that are either on or off ("binary"). In a way, neurons in the brain are either on or off by either firing an action potential or not firing an action potential. However, neurons are more than just on or off because the "excitability" of a neuron is always changing. This is because a neuron is constantly getting information from other cells through synaptic contacts. Information traveling across a synapse does NOT always result in a action potential. Rather, this information alters the chance that an action potential will be produced by raising or lowering the threshold of the neuron.
Both have a memory that can grow.
Computer memory grows by adding computer chips. Memories in the brain grow by stronger synaptic connections.
Both can adapt and learn.
It is much easier and faster for the brain to learn new things. Yet, the computer can do many complex tasks at the same time ("multitasking") that are difficult for the brain. For example, try counting backwards and multiplying 2 numbers at the same time. However, the brain also does some multitasking using the autonomic nervous system. For example, the brain controls breathing, heart rate and blood pressure at the same time it performs a mental task.
Both have evolved over time.
The human brain has weighed in at about 3 pounds for about the last 100,000 years. Computers have evolved much faster than the human brain. Computers have been around for only a few decades, yet rapid technological advancements have made computers faster, smaller and more powerful.
Both need energy.
The brain needs nutrients like oxygen and sugar for power the computer needs electricity to keep working.
Both can be damaged.
It is easier to fix a computer - just get new parts. There are no new or used parts for the brain. However, some work is being done with transplantation of nerve cells for certain neurological disorders such as Parkinson's disease. Both a computer and a brain can get "sick" - a computer can get a "virus" and there are many diseases that affect the brain. The brain has "built-in back up systems" in some cases. If one pathway in the brain is damaged, there is often another pathway that will take over this function of the damaged pathway.
Both can change and be modified.
The brain is always changing and being modified. There is no "off" for the brain - even when an animal is sleeping, its brain is still active and working. The computer only changes when new hardware or software is added or something is saved in memory. There IS an "off" for a computer. When the power to a computer is turned off, signals are not transmitted.
Both can do math and other logical tasks.
The computer is faster at doing logical things and computations. However, the brain is better at interpreting the outside world and coming up with new ideas. The brain is capable of imagination.
Both brains and computers are studied by scientists.
Scientists understand how computers work. There are thousands of neuroscientists studying the brain. Nevertheless, there is still much more to learn about the brain. "There is more we do NOT know about the brain, than what we do know about the brain"
This list describes only some of the similarities and differences between the computer and the brain. Can you think of any more? Try the Brain Metaphor page.