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Phineas Gage actually recovered from his personality change. A recent study was just published suggesting that most of what we thought we knew about Gage is incorrect, and he recovered from this extreme personality change. An emeritus professor, Richard Griggs, analysed over 23 books on Gage and came to the conclusion that he made a miraculous recovery, ...


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Gage suffered a massive injury to the frontal cortex due to his accident in 1848 (Fig.1). Recent work using computer assisted tomography (CAT) has shown that contrary to popular belief, the injury was probably not bilateral, but confined to the left-lateral frontal lobe (Ratiu et al, 2004). Fig.1. Original drawing of the wound sustained by Gage (left). ...


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Short answer The sodium-potassium pump in the epithelial cells lining the brain capillaries pumps Na+ and K+ into the brain. Background The blood-brain-barrier is formed by the endothelial cells lining the capillaries in the brain. Not many compounds can pass this lining, especially not when they are hydrophilic, such as charged metal ions. However, as you ...


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The cells/neurons themselves have Na+ and K+ channels in their cell membranes that allow for passive movement of these ions between the outside and inside of the cell. If you're wondering how the gradient gets established in the first place, simply put, these channels are built to open/close at the right amounts in their environments. Additionally, the cell ...


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Short answer Glutamate cannot enter the brain due to the blood-brain-barrier. Background You are totally right that glutamate represents the principal excitatory neurotransmitter in the brain (Meldrum, 2000). However, glutamate is a regular amino acid and will be metabolized quickly. More importantly, the blood-brain barrier is extremely effective in ...


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There is no strong evidence for MSG having any kind of neurotoxic/neuromodulatory effect. However, A 2010 article says that, in a double blind trial, it was found that the people who consumed MSG containing soda, reported headache in significantly more numbers compared to the placebo subjects [1]. The concentration of MSG used in this study was 75-150 ...


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Mordake was a conjoined twin fused at the head (Fig. 1). Twins conjoined at the heads are rare, occurring only once in every 2.5 million live births. Moreover, in Mordake's case it was a parasitic twin head with an undeveloped body that was fused with his own head. This condition is referred to as craniopagus parasiticus, or épicome / epicomus. Craniopagus ...


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Electricity directly stimulate neurons. You have to understand that neurons basically work via electric currents , which occur due to a difference in membrane charge. So when you give electricity to a neuron, you basically give electrons to the extracellular membrane, which makes it much more negative compared to the intracellular or the stuff that is inside ...


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You have to understand how the integral proteins work. $Na^+$ channels are fast while $K^+$ channels are slow and long lasting in terms of conductance. $Na^+$ channels are voltage gated, via the S4 domain which is blocked by $Mg^{2+}$, while $K^+$ conductance is not voltage gated most of the time.


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Short answer The activation kinetics of Na+ channels are faster than K+ channels. Background Voltage-dependent channel gating basically occurs through three possible states of the channel: open, closed and inactivated (Fig. 1). Fig. 1. Gating of a voltage-activated sodium channel. Source: Balseiro Institute. Basically, ion channels are protein pores in ...


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Electrical currents stimulate neurons aspecifically. For example, the BrainPort artificial vision device conveys information through electrical stimuluation of the tongue. Similarly, cochlear implants and retinal implants convey information through electrical stimulation of the inner ear and retina, respectively. The list goes on. Bottom line is, none of ...


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The "crash" effect is typically perceived as a deterioration in affect. With drugs, this deterioration happens as the drug is cleared from blood circulation, particularly cerebral circulation. With the ingestion of amphetamines, there is a brief reuptake of certain neurotransmitters, particularly dopamine and norepinephrine. Amphetamines also temporarily ...


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Like any statistical learner, the human brain surely experiences overfitting. You can convince people of lots of things that aren't true by showing them biased examples. That said, don't forget that the tasks by which we judge artificial intelligence are largely defined by what human brains happen to be good at. That's part of what makes us call it ...


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The neuronal cell membrane is quite permeable to K+. Because the Na+,K+-ATPase pumps K+ inside of the cell, K+ tends to diffuse outward again, thereby taking positive charge outside the cell and making it negative inside (see Further Reading 1). This outward flow of K+ stops at a certain point, because the driving force of K+ diffusion out of the cell along ...


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Frequency of tremor typically remains constant for the person. Levadopa (sinemet) does not change the frequency. Typically the tremor frequency will be in the range from 3Hz to 7Hz. There is a common phrase when dealing with PWP (Person With Parkinson's Disease). If you have seen one PWP, you have seen one PWP. Currently I am part of a study by the ...


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Neurons or nerve cells typically have a dendritic region, an axon and a cell body. The axon is also referred to as a nerve fiber. The axon is typically the longest structure, while the dendrites are mostly situated close to the cell body. See the following figure 1: Schematic of a nerve cell. Source: Prof. Brown. Axons often bundle into nerves. For ...


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It is something of a misnomer to speak of CSF “circulation,” particularly in the spinal canal, as there is no continuous loop circulation of CSF as there is in the cardiovascular system. For quite some time, it has been known that CSF movement results from the formation of new CSF and motion of cilia on the surface of the choroid plexus and ependyma ...


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CSF is actively pumped in an ebb and flow manner by the pressure with our respiratory mechanism transmitted through the pelvic diaphram onto the sacral bone that pulls on the spinal dural membranes attached at S2. Think about it: the pelvic and thoracic diaphragm are linked in a respiratory phasic contraction (confirmed with MRI). The pulling on the sacral ...


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Short answer The layers in the cortex are histologically and functionally defined. Both 3- and 6-layered cortices are found in the human brain. Hence, the different cortical layers are not models, but classifications based on empirical observations. Background The different cortical layers have been defined by histological staining and microscopy. The ...


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Short answer A rough indication of the delay in monosynaptically connected cortical neurons is 6 - 14 ms. Background As @Jonathan correctly states, there are many variables involved in neuronal delays. However, because you ask for an estimate of the order of magnitude of the neuronal delay between two coupled neurons in the neocortex, I will suffice by ...


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The conduction velocity can vary by orders of magnitude based on many factors, so more information would be needed for a useful answer. Unmyelinated axon conduction velocities range from about 0.5 to 10 m/s, whereas myelinated axon conduction velocities can reach up to 150 m/s1. I'm also not sure what you mean by "dense network". The brain is not a dense ...



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