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Short answer As far as I am aware, neurotoxic effects of chronic excitatory stimulation are not prevented by receptor trafficking. Background I think the question assumes that 1) neural damage related to continuous activation (excitotoxicity) is preventable by 2) the dynamic regulation of receptor numbers on the neuronal membrane. As far as I can see, ...


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In principle, many neurotransmitter receptors work as ion channels and the actual mechanism of signalling involves allowing the influx/efflux of calcium, potassium, magnesium, etc. A good example of this is the acetylcholine receptor. Presumably, if the cell retained the same number of receptors even in the presence of abundant ligands, the cell would flood ...


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I found two references that talk about the circle of Willis in different kind of mammals so i think it's right to say that this particular anastomotic system of arteries is not exclusive to humans. Here are the two references: http://www.neuroanatomy.org/2008/054_065.pdf http://www.ncbi.nlm.nih.gov/pubmed/14651482


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Feelings of pleasure and reward are transient in nature. Similarly, the dopamine release in the reward centers (the limbic structures) is transient, namely in the order of seconds (Rebec et al., 1997). One way to chronically elevate dopamine levels is by administering certain drugs. A notable/notorious example is methamphetamine, which elevates mood and ...


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The blood-brain barrier isn't a bag that surrounds the brain that you could puncture and then inject dopamine. It is a thin layer of cells around every blood vessel and capillary in the brain that mediate transfer of substances between the blood and the brain cells. As such, it is incredibly complex and branched (as complex and branched as the myriad blood ...


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Levo-Dopa is used as a first-line treatment of Parkinson's disease. Unlike dopamine, L-Dopa is able to cross the blood-brain barrier. There it is converted into dopamine. To prevent premature breakdown in the gastro-intestinal and circulatory system after oral intake, carbidopa can be co-administered. Also MAO-B inhibitors and COMT inhibitors can be applied ...


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A comment by @ddiez made a good point at identifying some ambiguity in the question: sight vs concentration. Sight has been answered well by @Ilan. You can't test to see if someone is squinting to concentrate. I stick by my original comment: Isn't it a social tool to show others you're thinking? It would be difficult to come up with a scientific ...


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The phenomenon in question is probably related to people with uncorrected/undercorrected myopia. This "ancient" phenomenon is called stenopeic slit effect (a case of pinhole effect): when the person squints the visual acuity becomes better because of smaller blur circles: the "slit" between the eyelids is the key point improving blurring. One can check if ...



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