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Tero Toivanen

AK's Rambling Thoughts: Nerve Cells and Glial Cells: Redefining the Foundation of Intel... - 0 views

  • Glia are generally divided into two broad classes, microglia and macroglia. Microglia are part of the immune system, specialized macrophages, and probably don't participate in information handling. Macroglia are present in both the peripheral and central nervous systems, in different types.
  • Traditionally, there were four types of glia in the CNS: astrocytes, oligodendrocytes, ependymal cells, and radial glia. Of these, the one type that's most important to the developing revolution in our ideas are those cells called astrocytes.2 It turns out that there are at least two types of cell (at least) subsumed under this name.24, 25, 31, 32 One, which retains the name of astrocyte, takes up neurotransmitters released by neurons (and glial cells), aids in osmoregulation,10 controls circulation in the brain,1, 31 and generally appears to provide support for the neurons and other types of glia.
  • Although both NG2-glia and astrocytes extend processes to nodes of Ranvier in white matter ([refs]) and synapses in grey matter, their geometric relationship to these neuronal elements is different. Thus, although astrocytes and NG2-glia bear a superficial resemblance, they are distinguished by their different process arborizations. This will reflect fundamental differences in the way these two glial cell populations interact with other elements in the neural network.
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  • Both types of glia are closely integrated with the nervous system, receiving information from action potentials via synapses22 (which, only a few years ago were thought to be limited to neurons), and returning control of neuron activity through release of neurotransmitters and other modulators. Both, then, demonstrate the potential for considerable intelligent activity, contributing to the overall intelligence of the brain.
  • Astrocytes probably (IMO) are limited, or mostly so, to maintaining the supplies of energy and necessary metabolites. They receive action potentials,3, 6 which allows them to closely and quickly monitor general activity and increase circulation in response, even before the neurons and NG2-glia have reduced their supply of ATP.21 They appear to be linked in a network among themselves,2, 5 allowing them to communicate their needs without interfering with the higher-level calculations of the brain.
  • NG2-glia appear to have several functions, but one of the most exciting things about them is that they seem to be able to fire action potentials.33 Their cell membranes, like those of the dendrites of neurons, have all the necessary channels and receptors to perform real-time electrical calculations in the same way as neural dendrites. They have also demonstrated the ability to learn through long term potentiation.
  • Dividing NG2-glia also retain the ability to fire action potentials, as well as receiving synaptic inputs from neurons.23 Presumably, they continue to perform their full function, including retaining any elements of long term potentiation or depression contained in their synapses.
  • Oligodendrocytes are responsible for the insulation of the axons, wrapping around approximately 1 mm of each of up to 50 axons within their reach, and forming the myelin sheath.
  • Although the precise type of neuron formed by maturing cells hasn't been determined, the very fact that cells of this type can change into neurons is very important. We actually don't know whether the cells that do this maturation are the same as those that perform neuron-like activities, there appear to be two separate types of NG2-glia, spiking and non-spiking.26 It may very well be that the "spiking" type have actually differentiated, while the "non-spiking" type may be doing the maturing. Of course, very few differentiated cell types remain capable of division, as even the "spiking" type do.
  • What's important about both dendrites and NG2-glia isn't so much their ability to propagate action potentials, as that their entire cell membranes are capable of "intelligent" manipulation of the voltage across it.
  • While there are many ion channels involved in controlling the voltage across the cell membrane, the only type we really need to worry about for action potentials is voltage-gated sodium channels. These are channels that sometimes allow sodium ions to pass through the cell membrane, which they will do because the concentration of sodium ions outside the cell is very much higher than inside. When and how much they open depends, among other things, on the voltage across the membrane.
  • A normal neuron will have a voltage of around -60 to -80mV (millivolts), in a direction that tends to push the sodium ions (which are positive) into the cell (the same direction as the concentration is pushing). When the voltage falls to around -55mV, the primary type of gate will open for a millisecond or so, after which it will close and rest for several milliseconds. It won't be able to open again until the voltage is somewhere between -55 and around -10mV. Meanwhile, the sodium current has caused the voltage to swing past zero to around +20mV.
  • When one part of the cell membrane is "depolarized" in this fashion, the voltage near it is also depressed. Thus, if the voltage is at zero at one point, it might be at -20mV 10 microns (μm) away, and -40mV 20μm away, and -60mV 30μm, and so on. Notice that somewhere between 20μm and 30μm, it has passed the threshold for the ion channels, which means that they are open, allowing a current that drives the voltage further down. This will produce a wave of voltage drop along the membrane, which is what the action potential is.
  • After the action potential has passed, and the gates have closed (see above), the voltage is recovered by diffusion of ions towards and away from the membrane, the opening of other gates (primarily potassium), and a set of pumps that push the ions back to their resting state. These pumps are mostly powered by the sodium gradient, except for the sodium/potassium pump that maintains it, which is powered by ATP.
  • the vast majority of calculation that goes into human intelligence takes place at the level of the network of dendrites and NG2-glia, with the whole system of axons, dendrites, and action potentials only carrying a tiny subset of the total information over long distances. This is especially important considering that the human brain has a much higher proportion of glial matter than our relatives.
  • This, in turn, suggests that our overall approach to understanding the brain has been far too axon centric, there needs to be a shift to a more membrane-centric approach to understanding how the brain creates intelligence.
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    Our traditional idea of how the brain works is based on the neuron: it fires action potentials, which travel along the axon and, when the reach the synapses, the receiving neuron performs a calculation that results in the decision when (or whether) to fire its own action potential. Thus, the brain, from a thinking point of view, is viewed as a network of neurons each performing its own calculation. This view, which I'm going to call the axon-centric view, is simplistic in many ways, and two recent papers add to it, pointing up the ways in which the glial cells of the brain participate in ongoing calculation as well as performing their more traditional support functions.
Tero Toivanen

'Noisiest' neurons persist in the adult brain - 0 views

  • In addition, the observation that the "noisiest" neurons have a survival advantage helps explain the prevalence of epilepsy, in which some neurons become hyperactive and fire in an uncontrollable fashion.
  • during childhood, when many neurons are still being added to the brain, it is likely that neurons that become pathologically hyperactive will be preferentially selected for survival, and these abnormal neurons will be the trigger for epilepsy,
  • Investigating the molecular signals launched by neuronal activity will potentially lead to new drugs that bolster the survival of new neurons. These drugs could be used to increase the efficacy of treatments that depend on grafting stem cell-derived neurons into the adult brain to treat neurological diseases such as Parkinson's and Alzheimer's.
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    'Noisiest' neurons persist in the adult brain
Tero Toivanen

Phasic Firing Of Dopamine Neurons Is Key To Brain's Prediction Of Rewards - 0 views

  • Our research findings provide a direct functional link between the bursting activity of midbrain dopamine neurons and behavior. The research has significant applications for the improvement of health, because the dopamine neurons we are studying are the same neurons that become inactivated during Parkinson's Disease and with the consumption of psychostimulants such as cocaine and amphetamine
  • Midbrain dopamine neurons fire in two characteristic modes, tonic and phasic, which are thought to modulate distinct aspects of behavior. When an unexpected reward is presented to an individual, midbrain dopamine neurons fire high frequency bursts of electrical activity. Those bursts of activity allow us to learn to associate the reward with cues in our environment, which may predict similar rewards in the future.
  • When researchers placed the mice in reward-based situations, they found that the mice without the NMDA receptor in their dopaminergic neurons could not learn tasks that required them to associate sensory cues with reward. Those same mice, however, were able to learn tasks that did not involve an association with rewards.
Tero Toivanen

VS Ramachandran: The neurons that shaped civilization - YouTube - 0 views

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    "Neuroscientist Vilayanur Ramachandran outlines the fascinating functions of mirror neurons. Only recently discovered, these neurons allow us to learn complex social behaviors, some of which formed the foundations of human civilization as we know it."
Tero Toivanen

AP Bio- Physiology 7: Neurons by David Knuffke on Prezi - 0 views

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    Great presentation about neurons.
Tero Toivanen

Brain Stimulant: Brain Chip to Restore Functioning from Damage - 1 views

  • The ReNaChip project is developing electronic biomimetic technology that could serve to replace damaged or missing brain tissue. This is basically neuromorphic engineering that seeks to mimic how neurons function. In the future this may be useful for people who have had injuries due to stroke or other illnesses.
  • The objective of this project is to develop a full biohybrid rehabilitation and substitution methodology; replacing the aged cerebellar brain circuit with a biomimetic chip bidirectionally interfaced to the inputs and outputs of the system. Information processing will interface with the cerebellum to actuate a normal, real-time functional behavioural recovery, providing a proof-of-concept test for the functional rehabilitation of more complex neuronal systems.
  • A sophisticated exocortex could potentially allow a two way communication between the external apparatus and the mind. The contraption could essentially scale up the amount of neurons in your brain by an artificial means. Most likely it would be used to improved the disabled first, with other applications being more speculative possibilities.
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    The ReNaChip project is developing electronic biomimetic technology that could serve to replace damaged or missing brain tissue. This is basically neuromorphic engineering that seeks to mimic how neurons function. In the future this may be useful for people who have had injuries due to stroke or other illnesses.
Tero Toivanen

Neurons lose information at one bit per second | KurzweilAI - 0 views

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    Approximately one bit of information disappears per active neuron per second.
Tero Toivanen

Discovery of quantum vibrations in microtubules inside brain neurons corroborates contr... - 0 views

  • A review and update of a controversial 20-year-old theory of consciousness published in  Elsevier’s Physics of Life Reviews (open access) claims that consciousness derives from deeper-level, finer-scale activities inside brain neurons. The recent discovery of quantum vibrations in microtubules inside brain neurons corroborates this theory, according to review authors Stuart Hameroff and Sir Roger Penrose.
Tero Toivanen

Map of Synapse May Help Understand Basis of Many Diseases - NYTimes.com - 3 views

  • The research team, led by Seth Grant of the Sanger Institute near Cambridge, England, compiled the first exact inventory of all the protein components of the synaptic information-processing machinery. No fewer than 1,461 proteins are involved in this biological machinery, they report in the current issue of Nature Neuroscience.
  • Each neuron in the human brain makes an average 1,000 or so connections with other neurons. There are 100 billion neurons, so the brain probably contains 100 trillion synapses, its most critical working part.
  • The 1,461 genes that specify these synaptic proteins constitute more than 7 percent of the human genome’s 20,000 protein-coding genes, an indication of the synapse’s complexity and importance.
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  • Dr. Grant believes that the proteins are probably linked together to form several biological machines that process the information and change the physical properties of the neuron as a way of laying down a memory.
  • The new catalog of synaptic proteins “should open a major new window in mental disease,” said Jeffrey Noebels, an expert on the genetics of epilepsy at the Baylor College of Medicine. “We can go in there and systematically look for disease pathways and therefore druggable targets.”
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    The research team, led by Seth Grant of the Sanger Institute near Cambridge, England, compiled the first exact inventory of all the protein components of the synaptic information-processing machinery. No fewer than 1,461 proteins are involved in this biological machinery
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    Seeing mental health as a druggable target is psychotic...
Tero Toivanen

YouTube - Neurons and How They Work - 0 views

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    Fantastic video in youtube about neurons and how they work,
David McGavock

Scientific Understanding of Consciousness - 0 views

  • During the past 20 years or so, biological sciences have advanced to the point that scientists have begun researching biological mechanisms of brain function and suggesting some reasonably well-founded hypotheses for consciousness. Leading the way in these pioneering efforts, in my judgment, have been:   Gerald Edelman with his hypothesis of the Dynamic Core, Antonio Damasio with his concepts of  Protoself, Core Self, Autobiographical Self, Core Consciousness and Extended Consciousness, Joseph LeDoux and his emphasis on the intricacies of synapses and the emotional brain,
  • Rudolfo Llinás and his researches into ~40 Hz oscillations and synchronization, György Buzsáki with his discussion and exploration of neural mechanisms related to oscillation and synchronization in the neocortex and hippocampus for perception and memory, Joaquín Fuster, the world’s preeminent expert on the frontal lobes, and his concept of the "perception-action cycle," Susan Greenfield's notion of "neuronal gestalts" as a way of conceptualizing a highly variable aggregation of neurons that is temporarily recruited around a triggering epicenter. I use the neuronal gestalts idea in my way of visualizing the functionality of the dynamic core of the thalamocortical system, Eric Kandel who has explored short-term and long-term memory,
  • The late Francis Crick with his collaborator Christof Koch who have pursued the neural correlate of consciousness (NCC), Michael Gazzaniga with the concept of the left hemisphere ‘interpreter’ unifying consciousness experience, Edmund Rolls and Gustavo Deco with their mathematical models of brain function using information theory approaches for biologically plausible neurodynamical modeling of cognitive phenomena corroborated by brain imaging studies, David LaBerge with his discussion of the thalamocortical circuit and attention, Alan Baddeley who continues to refine his model for working memory, Philosopher John Searle who endorses the idea that consciousness is an emergent property of neural networks.
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    "My objective in this website has been to bring together salient features of these assorted interpretations by science experts into a synthesis of my own understanding of consciousness. I consider these statements and interpretations to be a framework on which to build a fuller understanding as further data, concepts and insights develop from ongoing research."
Tero Toivanen

Scientists capture the first image of memories being made - 0 views

  • A new study by researchers at the Montreal Neurological Institute and Hospital (The Neuro), McGill University and University of California, Los Angeles has captured an image for the first time of a mechanism, specifically protein translation, which underlies long-term memory formation. The finding provides the first visual evidence that when a new memory is formed new proteins are made locally at the synapse - the connection between nerve cells - increasing the strength of the synaptic connection and reinforcing the memory. The study published in Science, is important for understanding how memory traces are created and the ability to monitor it in real time will allow a detailed understanding of how memories are formed.
  • research has focused on synapses which are the main site of exchange and storage in the brain.
  • They form a vast but also constantly fluctuating network of connections whose ability to change and adapt, called synaptic plasticity, may be the fundamental basis of learning and memory.
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  • Using a translational reporter, a fluorescent protein that can be easily detected and tracked, we directly visualized the increased local translation, or protein synthesis, during memory formation.
  • Importantly, this translation was synapse-specific and it required activation of the post-synaptic cell, showing that this step required cooperation between the pre and post-synaptic compartments, the parts of the two neurons that meet at the synapse.
  • This study provides evidence that a mechanism that mediates this gene expression during neuronal plasticity involves regulated translation of localized mRNA at stimulated synapses.
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    A new study by researchers at the Montreal Neurological Institute and Hospital (The Neuro), McGill University and University of California, Los Angeles has captured an image for the first time of a mechanism, specifically protein translation, which underlies long-term memory formation.
Tero Toivanen

» Brain Plasticity: How learning changes your brain   « Brain Fitness Revolut... - 0 views

  • A surprising consequence of neuroplasticity is that the brain activity associated with a given function can move to a different location as a consequence of normal experience, brain damage or recovery.
  • The brain compensates for damage by reorganizing and forming new connections between intact neurons. In order to reconnect, the neurons need to be stimulated through activity.
  • Research has shown that in fact the brain never stops changing through learning. Plasticity IS the capacity of the brain to change with learning. Changes associated with learning occur mostly at the level of the connections between neurons. New connections can form and the internal structure of the existing synapses can change.
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  • It looks like learning a second language is possible through functional changes in the brain: the left inferior parietal cortex is larger in bilingual brains than in monolingual brains.
  • For instance, London taxi drivers have a larger hippocampus (in the posterior region) than London bus drivers (Maguire, Woollett, & Spiers, 2006)…. Why is that? It is because this region of the hippocampus is specialized in acquiring and using complex spatial information in order to navigate efficiently. Taxi drivers have to navigate around London whereas bus drivers follow a limited set of routes.
  • Did you know that when you become an expert in a specific domain, the areas in your brain that deal with this type of skill will grow?
  • Plastic changes also occur in musicians brains compared to non-musicians.
  • They found that gray matter (cortex) volume was highest in professional musicians, intermediate in amateur musicians, and lowest in non-musicians in several brain areas involved in playing music: motor regions, anterior superior parietal areas and inferior temporal areas.
  • Medical students’ brains showed learning-induced changes in regions of the parietal cortex as well as in the posterior hippocampus. These regions of the brains are known to be involved in memory retrieval and learning.
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    A surprising consequence of neuroplasticity is that the brain activity associated with a given function can move to a different location as a consequence of normal experience, brain damage or recovery.
Tero Toivanen

http://www.sciencedaily.com/releases/2009/12/091223125125.htm - 1 views

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    Scientists at UC Santa Barbara have made a major discovery in how the brain encodes memories. The finding, published in the December 24 issue of the journal Neuron, could eventually lead to the development of new drugs to aid memory.
Tero Toivanen

Use It or Lose It: The Principles of Brain Plasticity - 3 views

  • You probably haven't realizd it, but as you acquire an ability – for example, the ability to read – you have actually created a system in the brain that does not exist, that's not in place, in the non-reader. It [the ability; the brain system that controls the ability] actually evolves in you as it has been acquired through experience or learning.
  • "There are some very useful exercises at www.BrainHQ.com that are free, and using them can give a person a better understanding of how exercising your brain can drive it in a rejuvenating direction. Using exercises at BrainHQ, most people, of any age, can drive sharp improvements in brain speed and accuracy, and thereby rewire the brain so that it again represents information in detail," he says.
  • Children operating in the 10th to 20th percentile of academic performance are commonly able to improve their scores to the middle or average level with 20-30 hours of intensive computer-based training. "That's a big difference for the child," he says. "It carries most children who are near the bottom of the class, on the average, to be somewhere in the middle or above average in the class. And that gives struggling children a chance to really succeed and in many cases excel in school."
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  • Careful controlled studies in seniors have also been reported in scientific journals. After 40 hours of computer-based training, the average improvement in cognitive performance across the board was 14 years. On average, if you were 70 years old when you underwent the training after 40 hours of brain training, your cognitive abilities operated like that of a 56-year old. Equally strong or even greater effects were seen in 40 to 50 year olds using the program. Individuals who worked on the BrainHQ exercises at home did just as well as those who completed training in a clinic or research center.
  • Ideally, it would be wise to invest at least 20 minutes a day. But no more than five to seven minutes is to be spent on a specific task. When you spend longer amounts of time on a task, the benefits weaken. According to Dr. Merzenich, the primary benefits occur in the first five or six minutes of the task.
  • Find ways to engage yourself in new learning
  • "When it matters to you, you are going to drive changes in your brain," he explains. "That's something always to keep in mind. If what you're doing seems senseless, meaningless, if it does not matter to you, then you're gaining less from it."
  • Get 15-30 minutes of physical exercise each day,
  • Spend about five minutes every day working on the refinement of a specific, small domain of your physical body.
  • You can typically improve yourself to the highest practical or possible level in anywhere between five to a dozen brief sessions of seven or eight minutes each. Again, having a sense of purpose is crucial.
  • Stay socially engaged.
  • Practice "mindfulness,"
  • Foods have an immense impact on your brain, and eating whole foods as described in my nutrition plan will best support your mental and physical health.
  • The medical literature is also showing that coconut oil can be of particular benefit for brain health, and anecdotal evidence suggests it could be very beneficial in the treatment of Alzheimer's disease.
  • Optimize your vitamin D levels
  • Take a high-quality animal-based omega-3 fat.
  • Avoid processed foods and sugars, especially fructose
  • Avoid grains
  • Avoid artificial sweeteners
  • Avoid soy
  • Men who ate tofu at least twice weekly had more cognitive impairment, compared with those who rarely or never ate the soybean curd, and their cognitive test results were about equivalent to what they would have been if they were five years older than their current age.
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    "It was once thought that any brain function lost was irretrievable. Today, research into what's referred to as "brain plasticity" has proven that this is not the case. On the contrary, your brain continues to make new neurons throughout life in response to mental activity."
Tero Toivanen

Scientists discover how brain cells age | KurzweilAI - 2 views

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    "Now scientists at Newcastle University, led by Professor Thomas von Zglinicki, have shown that neurons in fact follow the same pathway as senescing fibroblasts, the cells that divide in the skin to repair wounds."
Tero Toivanen

Things I like to Blog About: Neurotransmission : Neurotopia - 0 views

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    Neurotransmission explained in an easy way.
Tero Toivanen

NIMH · Our brains are made of the same stuff, despite DNA differences - 0 views

  • “Having at our fingertips detailed information about when and where specific gene products are expressed in the brain brings new hope for understanding how this process can go awry in schizophrenia, autism and other brain disorders,” said NIMH Director Thomas R. Insel, M.D.
  • Among key findings in the prefrontal cortex:Individual genetic variations are profoundly linked to expression patterns. The most similarity across individuals is detected early in development and again as we approach the end of life.Different types of related genes are expressed during prenatal development, infancy, and childhood, so that each of these stages shows a relatively distinct transcriptional identity. Three-fourths of genes reverse their direction of expression after birth, with most switching from on to off.Expression of genes involved in cell division declines prenatally and in infancy, while expression of genes important for making synapses, or connections between brain cells, increases. In contrast, genes required for neuronal projections decline after birth – likely as unused connections are pruned.By the time we reach our 50s, overall gene expression begins to increase, mirroring the sharp reversal of fetal expression changes that occur in infancy.Genetic variation in the genome as a whole showed no effect on variation in the transcriptome as a whole, despite how genetically distant individuals might be. Hence, human cortexes have a consistent molecular architecture, despite our diversity.
  • Among key findings:Over 90 percent of the genes expressed in the brain are differentially regulated across brain regions and/or over developmental time periods. There are also widespread differences across region and time periods in the combination of a gene’s exons that are expressed.Timing and location are far more influential in regulating gene expression than gender, ethnicity or individual variation.Among 29 modules of co-expressed genes identified, each had distinct expression patterns and represented different biological processes. Genetic variation in some of the most well-connected genes in these modules, called hub genes, has previously been linked to mental disorders, including schizophrenia and depression.Telltale similarities in expression profiles with genes previously implicated in schizophrenia and autism are providing leads to discovery of other genes potentially involved in those disorders.Sex differences in the risk for certain mental disorders may be traceable to transcriptional mechanisms. More than three-fourths of 159 genes expressed differentially between the sexes were male-biased, most prenatally. Some genes found to have such sex-biased expression had previously been associated with disorders that affect males more than females, such as schizophrenia, Williams syndrome, and autism.
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  • Our brains are all made of the same stuff. Despite individual and ethnic genetic diversity, our prefrontal cortex shows a consistent molecular architecture.
  • Males show more sex-biased gene expression. More genes differentially expressed (DEX) between the sexes were found in males than females, especially prenatally. Some genes found to have such sex-biased expression had previously been associated with disorders that affect males more than females, such as schizophrenia, Williams syndrome, and autism.
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    Our brains are all made of the same stuff. Despite individual and ethnic genetic diversity, our prefrontal cortex shows a consistent molecular architecture. 
Tero Toivanen

Your Brain at Work - YouTube - 0 views

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    This is Fantastic!
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    This is Fantastic! via Jesse Soininen
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