16 votes
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How does methamphetamine (meth) damage neurons?

Nice question! I will directly begin with the process through which methamphetamine causes damage to neurons, putting in as much details as are known, and adding appropriate citations wherever ...
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14 votes
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Is brain transplantation possible?

Short answer Yes, brain transplantation is technically possible, but only for short periods of time, and only in experimental settings. Background In terms of a full-brain transplant there has ...
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  • 51k
14 votes

What is the cause that angina pectoris is felt in your left arm?

It has mainly to do with the embryonic origin of organs, with the heart being a typically left sided organ, it develops sharing some nerves with the left thorax and left arm. There is however high ...
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10 votes
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How long can the brain survive during ongoing cardiac arrest?

From Boron and Boulpaep textbook of Medical Physiology, second edition, p.289: Because of falling ATP levels in the brain, consciousness is lost within 10 seconds of a blockade in cerebral blood ...
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  • 3,010
8 votes
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Is it possible to process electrical signals from the brain and interpret the results as exact thoughts?

The brain activity is electric and chemical. The male adult human brain contains about 86 billion neurons (Azevedo et al). There is about 100 trillion connections between them. Solving a puzzle like ...
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  • 96
8 votes
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Why Is Gray Matter Gray?

The terms gray and white matter relate to their color in gross specimens (i.e., not microscopic specimens) that have been formalin fixed. Nissl granules describe a microscopic structure, the rough ...
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  • 8,671
7 votes
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What causes the range of severity of neurological deficits in Down's syndrome?

The symptoms of Down syndrome occur due to overexpression of genes present on the duplicated chromosome. If possessing an extra chromosome meant an equivalent change in gene expression, one would ...
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7 votes

What is synaptic bias?

Often artificial neurons are created with conventions that zero is "rest" and 1 is "threshold". The unit starts at 0, and when it reaches 1 it will send an input to all of its targets and be reset ...
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  • 34.9k
7 votes
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Are there any known rules that neurons always follow while transmitting/receiving signals?

Short Answer: "Always" is always a dangerous term in biology. Longer Answer: What does a neuron do if it does not get stimulated/receives no signal for a long time. Will it die ... or try to find ...
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  • 34.9k
6 votes
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Can rapid eye blinking induce epileptic seizures?

“Self-induction” in photosensitive epilepsy is a well-described and fascinating phenomenon. Photosensitivity itself is rare, occurring in only ~5% of patients with epilepsy.1 Among this group it has ...
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  • 3,119
6 votes

What is the biological principle of this "holotropic breathwork" technique?

I think this is mostly caused by hyperventilation. The excessive breathing disturbs the balance between CO$_{2}$ and oxygen in our lungs. This will cause respiratory alkalosis (the blood pH, which is ...
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  • 49.1k
6 votes
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What is two photon calcium imaging?

what does the "two photon" means? Ordinary confocal microscopy uses single photon of laser light to excite the molecule of fluorescent dye. In two photon microscopy you use two photons, with lower ...
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  • 716
6 votes
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If action potential is "all or nothing" then how are finely tuned signals sent from one neuron to another?

how is one type of neurotransmitter secreted rather than another Most neurons release a single major neurotransmitter. JM97 commented a link about cells releasing more than one, but that is talking ...
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  • 34.9k
6 votes

Neuron connectivity- how are they connected physically

Neurons are suspended, as you say, in an extracellular matrix. Brain tissues are a little bit more specific. Here I quote a few summaries from literature to answer and give your a perspective on your ...
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  • 5,582
5 votes

What is accumulation and release centre of neurohormones?

The neurohormones in most mammals include oxytocin and vasopressin, both of which are produced in the hypothalamic region of the brain and secreted into the blood by the neurohypophysis (part of the ...
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  • 181
5 votes
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Is it possible to be (briefly) aware you had been decapitated?

According to this, in rats it takes about 17 seconds after decapitation for the EEG to become iso-electric. But there is no known correlation between EEG and consciousness. Also at 50-80 seconds after ...
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  • 7,047
5 votes
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Neuroscience of mathematicians

Short answer People competent in mathematics have been shown to have higher activation of the left angular gyrus according to fMRI. EEG recordings have shown larger activity in the posterior parietal ...
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  • 51k
5 votes

What is the cause that angina pectoris is felt in your left arm?

Our pain-sensing neurons work in useful ways only when they inform about skin areas or muscles. When nettles sting your left hand, you want to retract your left hand right away. This is in part an ...
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  • 1,120
5 votes
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Why do polyneuropathies affect the extremities first?

Polyneuropathy is actually not a very specific term, so the reasons will no doubt vary depending on which specific class you are talking about. That said, here are two reasons that longer neurons are ...
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  • 34.9k
5 votes
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Why can't dopamine cross the blood brain barrier but l-dopa can?

Both L-Dopa and Dopamine are polar molecules and thus hydrophilic. They are solvable in water but not in lipids, so they are not able to cross the Blood-brain barrier on their own. The difference is ...
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  • 262
5 votes
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If the Brain can store as much information as a billion hard disks why cant i memorize a single word document of random letters?

The brain is trained to remember patterns and predictable associations. Randomness is the absence of patterns, so it's the exact opposite of what the human brain is for. A human can remember random ...
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5 votes

Appropriate cell lines to study depression

tl;dr there is no 'depression' cell line. Cell lines would be suited for studying pharmacology, cellular or molecular mechanisms, none of which are depression. Depression also has no good correlates ...
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  • 5,582
4 votes

EM Brainwaves VS Brain Wave (EEG)

I assume with EM you refer to electromagnetic? You are right that the EEG (electroencephalogram) is a tiny signal. When about 50.000 neurons fire simultaneously, it possible to see a change in the ...
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  • 41
4 votes
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Is it possible for neurons themselves to manifest cancerous behavior?

Yes, but rarely. Other types of brain cells are much more likely to form tumors. Oligodendrocytes, astrocytes, and more generally glial cells all form tumors with some regularity. Nerve sheaths can ...
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  • 3,978
4 votes

Hebbian theory "fire together" clarification

Strictly stated, Hebb's rule applies only to existing synapses, and not to the formation of new synapses. (This answer applies to biological neurons, not to ANNs). Synapse formation is a topic of ...
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4 votes

Alpha wave frequency variance in EEG of single subject over period of a few hours?

I noticed that a strong background signal in the alpha-wave range was existent at ~10 Hz, but then after a while of doing other things and coming back to it the strong background signal at 10 Hz ...
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  • 181
4 votes

How do humans perceive time?

The nature of time has been discussed for millenia. We don't know exactly why or where time perception exists, but we do have some information on how it is perceived. The circadian rhythm is ...
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4 votes
Accepted

Is there any way a human could whistle and be unable to speak?

Short answer(s) Someone with a damaged larynx may still speak with the use of a speech aid (electronic larynx). The ability to understand speech does not necessarily mean one can speak normally. ...
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  • 51k
4 votes

Is there any way a human could whistle and be unable to speak?

You can whisper without a larynx. "Patients who have undergone partial or full laryngectomy are typically unable to speak anything more than hoarse whispers, without the aid of prostheses or ...
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