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Tero Toivanen

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

artksthoughts.blogspot.com/...nd-glial-cells-redefining.html

brain Glial Cells neuron action potential axon synapse network microglia macroglia astrocytes oligodendrocytes ependymal cells radial glia

shared by Tero Toivanen on 25 Jun 09 - Cached
  • 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.
  • Tero Toivanen on 25 Jun 09
     
    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

Selective aphasia in a brain damaged bilingual patient : Neurophilosophy - 0 views

scienceblogs.com/...damageed_bilungual_patient.php

brain bilingual Arabic Hebrew CT scan frontal lobe parietal lobe crationomy hemorrhage

shared by Tero Toivanen on 11 Jul 09 - Cached
  • A unique case study published in the open access journal Behavioral and Brain Functions sheds some light on this matter. The study, by Raphiq Ibrahim, a neurologist at the University of Haifa, describes a bilingual Arabic-Hebrew speaker who incurred brain damage following a viral infection. Consequently, the patient experienced severe deficits in Hebrew but not in Arabic. The findings support the view that specific components of a first and second language are represented by different substrates in the brain.
  • A native Arabic speaker, he learned Hebrew at an early age (4th grade) and later used it competently both professionally and academically.
  • A CT scan showed that he had suffered a massive hemorrhage in the left temporal lobe, which was compressing the tissue on both sides of the central sulcus, the prominent gfissure which separates the frontal and parietal lobes.
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  • A craniotomy was performed to relieve the pressure, and afterwards another scan showed moderate hemorrhage and herpes encephalitis in the left temporal lobe, and another hemorrhage beneath the outer membrane (the dura) lying over the right frontal lobe.
  • During his 2 month stay there, he developed epileptic seizures which originated in the left temporal lobe, and amnestic aphasia (an inability to name objects or to recognize their written or spoken names). 
  • After the rehabilitation period, a series of linguistic tests was administered to determine the extent of his speech deficits. M.H. exhibited deficits in both languages, but the most severe deficits were seen only in Hebrew. In this language he had a severe difficulty in recalling words and names, so that his speech was non-fluent and interrupted by frequent pauses. He had difficulty understanding others' spoken Hebrew, and also had great difficulty reading and writing Hebrew. In Arabic, his native language, all of these abilities were affected only mildy.
  • The results support a neurolinguistic model in which the brain of bilinguals contains a semantic system (which represents word meanings) which is common to both languages and which is connected to independent lexical systems (which encode the vocabulary of each language). The findings further suggest that the second language (in this case, Hebrew) is represented by an independent subsystem which does not represent the first language (Arabic) and is more succeptible to brain damage.
  • Tero Toivanen on 11 Jul 09
     
    A unique case study published in the open access journal Behavioral and Brain Functions sheds some light on this matter. The study, by Raphiq Ibrahim, a neurologist at the University of Haifa, describes a bilingual Arabic-Hebrew speaker who incurred brain damage following a viral infection. Consequently, the patient experienced severe deficits in Hebrew but not in Arabic. The findings support the view that specific components of a first and second language are represented by different substrates in the brain.
Tero Toivanen

YouTube - Science Commons by Jesse Dylan (Español) - 0 views

www.youtube.com/watch

Common Science science research open youtube

shared by Tero Toivanen on 29 Jun 09 - Cached
  • Tero Toivanen on 29 Jun 09
     
    It's time for Common Science. Open research and science.
Tero Toivanen

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

www.kurzweilai.net/ar-old-theory-of-consciousness

quantum brain theory consciousness research neuroscience neurons

shared by Tero Toivanen on 17 Jan 14 - No Cached
  • 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

Visual training to retain driving competence - and your independence! | On the Brain by... - 1 views

merzenich.positscience.com/?p=250

brain visual training automobile drivers DriveSharp merzenich

shared by Tero Toivanen on 19 Jul 09 - Cached
  • Today, Posit Science announced the release of a new computer-based visual training tool, DriveSharp, specifically designed to improve the performance abilities of adult automobile drivers to a degree that can be expected to very substantially impact their driving safety.
  • Again, with a few hours of intensive training, a youthful MOT performance level can be achieved for most individuals. The result: A still FURTHER increase of driving safety.
  • In our fast-moving world, losing control of one’s peripheral vision is a main cause of driving accidents.
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  • Ball and Roenker demonstrated that these losses are substantially reversible, through appropriate, intensive training, in almost all older drivers. UFOVs can be re-expanded to relatively youthful ability levels through only a few hours of exercise. The result: About 50% fewer driving accidents in the over-65 population.
  • Moreover, once your UFOV is opened up again, you use it!
  • You can use DriveSharp repeatedly, over the rest of your days, to keep yourself in fine driving fettle!
  • The second training program that is included in DriveSharp is designed to improve your ability to keep track of more than one thing happening at the same time. This fundamental visual skill — called “multiple object tracking” (MOT) — also dramatically declines as you get older.
  • As you get older, you progressively lose the ability to accurately detect and respond to visual events in your far visual periphery.
  • If you’ve reached your 50th birthday, DriveSharp training is especially important for upgrading and sustaining your driving competence. It’s all about maintaining your performance abilities in driving as in all other ways at the highest possible level, throughout the second half of life.
  • few other benefits demonstrated by published studies originating with the Ball/Roenker team (including University of South Florida scientist Sherri Willis and a University of Iowa scientist, Fred Wolinsky).
  • 1) You’re healthier after DriveSharp training! Five years after training, Physical indices of Quality of Life are more than 30% higher — maybe because you get out more.
  • Trainees are much more likely to have retained your driver’s license — and to have sustained their personal independence.
  • After DriveSharp, you are a more confident driver, as expressed by gains in the number of times you drive each week, by an increase in average driving distances, and by your driving more often at night, or in the rain or snow.
  • Try DriveSharp now: If you are a member of one of the participating AAA clubs, please visit your AAA club’s website for more information and a special offer on DriveSharp. If not, please visit www.DriveSharp.com or call (866)599-6463 to learn more.
  • Tero Toivanen on 19 Jul 09
     
    Today, Posit Science announced the release of a new computer-based visual training tool, DriveSharp, specifically designed to improve the performance abilities of adult automobile drivers to a degree that can be expected to very substantially impact their driving safety.
Tero Toivanen

Low Pessimism Protects Against Stroke: The Health and Social Support (HeSSup) Prospecti... - 2 views

stroke.ahajournals.org/...187

pessimism optimism stroke brain research

shared by Tero Toivanen on 07 Jan 10 - Cached
  • Tero Toivanen on 07 Jan 10
     
    It's good for your life and health to be optimist.
  • Ruth Howard on 11 Jan 10
     
    It' s a slightly different perspective that I' m enjoying at this time but I appreciate it may only be true for some-I' ve just begun to understand what "faith" means tho I' m not religious-still! (I feel some empathy now as to why people are) I feel much more inclined to just sit still and connect inside with the Source of me-any meditation or spiritual practice can lead me there or creativity,music too,nature! But to deliberately connect to the part of us all that is connected and knows/is All. From that place I' ve understood that theres noone to be, nowhere to go, nothing to do as we are all there already as we are all IT! So of course daily I forget this but this insight has gifted me much more optimism as I can assume that whatever I really ask for/intend/desire is already in the big melting pot that we can Life/God. That is ' faith' Ive realised now- to ask and know intimately that it' s already a given and to STOP Worrying and completely ignore the naysayers etc. It' s really trusting that I' m connected to it all and I am not separate. I' m beginning to observe quite distinctly the thoughts that separate me from what I want/intend. Particularly in relation to my fellow beings! But then I turn to the place that is connected and I feel so good! and just thinking of the situation from that place and holding that good feeling in relation and giving it over (the problem) really helps! I know several spiritual teachers have said "give it over to me". I' m starting to understand it really is that simple. Trying hard and worrying just create such muck and mire! This may be part of the surrender letting go and letting God that others speak of also? I reckon it would be interesting to see where how people get there faith/trust in life that creates the underlying optimism. What gives that to them? I remember as a child I had it naturally I often got what I asked for and intended and there was an abundance of flow and optimism. No resistance. Fear and doubt come later
Tero Toivanen

Adult Learning - Neuroscience - How to Train the Aging Brain - NYTimes.com - 1 views

www.nytimes.com/...03adult-t.html

neuroscience brain aging adult learning tots research training

shared by Tero Toivanen on 02 Jan 10 - Cached
  • One explanation for how this occurs comes from Deborah M. Burke, a professor of psychology at Pomona College in California. Dr. Burke has done research on “tots,” those tip-of-the-tongue times when you know something but can’t quite call it to mind. Dr. Burke’s research shows that such incidents increase in part because neural connections, which receive, process and transmit information, can weaken with disuse or age.
  • But she also finds that if you are primed with sounds that are close to those you’re trying to remember — say someone talks about cherry pits as you try to recall Brad Pitt’s name — suddenly the lost name will pop into mind. The similarity in sounds can jump-start a limp brain connection. (It also sometimes works to silently run through the alphabet until landing on the first letter of the wayward word.)
  • Recently, researchers have found even more positive news. The brain, as it traverses middle age, gets better at recognizing the central idea, the big picture. If kept in good shape, the brain can continue to build pathways that help its owner recognize patterns and, as a consequence, see significance and even solutions much faster than a young person can.
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  • The trick is finding ways to keep brain connections in good condition and to grow more of them.
  • Educators say that, for adults, one way to nudge neurons in the right direction is to challenge the very assumptions they have worked so hard to accumulate while young. With a brain already full of well-connected pathways, adult learners should “jiggle their synapses a bit” by confronting thoughts that are contrary to their own, says Dr. Taylor, who is 66.
  • Teaching new facts should not be the focus of adult education, she says. Instead, continued brain development and a richer form of learning may require that you “bump up against people and ideas” that are different. In a history class, that might mean reading multiple viewpoints, and then prying open brain networks by reflecting on how what was learned has changed your view of the world.
  • Such stretching is exactly what scientists say best keeps a brain in tune: get out of the comfort zone to push and nourish your brain. Do anything from learning a foreign language to taking a different route to work.
  • “As adults we have these well-trodden paths in our synapses,” Dr. Taylor says. “We have to crack the cognitive egg and scramble it up. And if you learn something this way, when you think of it again you’ll have an overlay of complexity you didn’t have before — and help your brain keep developing as well.”
  • Tero Toivanen on 02 Jan 10
     
    Dr. Burke has done research on "tots," those tip-of-the-tongue times when you know something but can't quite call it to mind. Dr. Burke's research shows that such incidents increase in part because neural connections, which receive, process and transmit information, can weaken with disuse or age.
Tero Toivanen

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

www.nytimes.com/...21brain.html

synapse map brain research neuroscience neurons science

shared by Tero Toivanen on 22 Dec 10 - No Cached
  • 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.”
  • Tero Toivanen on 22 Dec 10
     
    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
  • Ruth Howard on 26 Dec 10
     
    Seeing mental health as a druggable target is psychotic...
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