The study of the structure and function of the nervous system and its components.

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Why does the human brain not overfit when training at some task?

One of the problems that occur during (artificial) neural network training is called overfitting. The error on the training set is driven to a very small value, but when new data is presented to the ...
8
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1answer
71 views

Original paper about the all or none law for neurons

I am looking for the original paper about the all or none law for neural activity. I know that there is a very old article about the all or none law for mammalian heart muscle fibers, but I'm ...
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2answers
184 views

Understanding the brain: how are neurotransmitters released in the brain?

I have a basic knowledge of how neural networks work. A potential difference is created that forces sodium, potassium, chloride, and calcium ions to flow which carries an electrical signal to the end ...
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2answers
53 views

What is synaptic clearance?

Please explain what the term synaptic clearance means. For example, what would dopamine synaptic clearance be? It is important to me in context of dopamine signaling variation due to difference in ...
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1answer
49 views

How does the brain train its neural network?

One question that came up learning how artificial neural networks are working was how the brain can train its neural network? When we say we have an artificial neural network, the problem behind it ...
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1answer
98 views

What is the direction of current flow in myelinated nerve cells?

Is it correct to say electric current flows through the extracellular space, or cytosol of a nerve fiber during impulse conduction? I know that an impulse is actually a change of membrane potential ...
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34 views

Transcranial Magnetic Stimulation on science fair [closed]

My friends and I would love to make a TMS machine and apply it to make famous "god helmet". We know that magnetic stimulation may cause visions of angels, gods etc. My question is: what are the ...
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4answers
3k views

Why do smaller mammals move intermittently?

I was watching a nice little video on youtube but couldn't help but notice how snappy smaller animals such as rats and chipmunks move. By snappy I mean how the animal moves in almost discrete states ...
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1answer
19 views

Are cortical columns restricted to somatosensory cortical sections?

From this previous question, it seems like evidence for the minicolumn organisation of the neocortex seems to be primarily based off observations around the sensory parts of the cortex, such as the ...
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18 views

Pearson correlation of neural responses with it's linear estimation

I am trying to anderstand the following fact from this article (page 13): How can single neurons predict behavior Suppose I have a linear estimation of a stimulus: $ \hat{s} = \mathbf{w}^T(\mathbf{r} ...
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1answer
300 views

What keeps the resting potential of neurons constant at -70 mV?

I know the sodium-potassium pump pumps out 3 Na+ ions and pumps in 2 K+ ions per reaction so the negative charge in the axon increases. However, once the voltage (difference of charge inside and ...
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0answers
38 views

Why are oral cells (or tissues) more heat resistant? [closed]

When we are having meals, such as enjoying hot pot and drinking hot water, we only have a sense of "warm" in our mouth, or even along the organs in alimentary canal. But when we put our fingers into ...
7
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1answer
114 views

The mechanism of mechanoreception?

I am interested in knowing the molecular mechanism behind mechanoreception/mechanotransduction (i.e. mechanism behind receptor potential generation on mechanical stimulation). I know that most ...
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3answers
461 views

What exactly is the neural receptive field?

Neural receptive fields map the spatial or temporal distribution of the data to individual neuron excitation, if I understand correctly, but I do not understand if receptive fields (especially in the ...
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1answer
91 views

Anatomy of nervous system's sensory pathways

When I touch my hand on a hot stove, I feel pain. I'm interested in knowing all the main "endpoints" (components/parts of the body) that are involved in relaying this pain signal. As I understand it ...
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1answer
525 views

Relationship between nerves and axons

I just wanted to get a realistic viewpoint of our nervous system. I understand arteries and veins, but I wanted to know how similar our nervous system is to that? I understand we have neurons (...
3
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1answer
69 views

spinal cord lesion and result in somatic sensation

Jimbo suffers a lesion to the entire right half of the spinal cord at the T6 level. A few weeks after his injury, his doctor tests his right and left legs for somatic sensation and tone. fill out her ...
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1answer
72 views

What stimulates a nociceptor?

For instance, when pressure is applied to the skin, what determines how much pressure results in nociceptor stimulation. And when a sharp object pierces the skin, why is pain, rather than simply touch,...
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1answer
258 views

Do taller people have larger somatosensory cortices than short people?

When we assume that peripheral touch receptor densities are equal in tall and short people, then tall people should have more touch receptors than short people, given the larger amount of skin surface ...
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1answer
1k views

Why does it hurt more when you touch a nerve directly?

I am not a biologist nor know much about biology (so please explain in layman's terms) however I have always been curious as to why this is. What causes the difference in pain between touching an ...
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1answer
54 views

What could cause no pain but sense of touch?

What could cause a mammal to have and respond to a sense of touch with only isolated numbness but not feel pain?
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2answers
99 views

Is numbness the absence of one or all touch sensations?

I am studying the effects of tetrodotoxin and its symptoms when consumed. Numbness is one of the first sensations reported. But I googled numbness and I couldn't find information about whether this ...
4
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2answers
84 views

How does valerian make you calmer?

Why do Valerian pills make us calmer? What is the mechanism behind it? I understand how artificial tranquilizers work. Do valerian pill have similar chemical components?
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1answer
179 views

Biological implementation of convolutional neural networks

In computer science, 'convolutional neural networks' are used, that are meant to be inspired by biological network structures like found in the human brain visual cortex. In the computer ...
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1answer
154 views

Can the dendrites of sensory neurons be a meter long?

The typical textbook structure of neurons is a cell with a short dendritic tree and a long axon. The dendrites receive information and send it to the axon via the cell body (soma). The axon is a long ...
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1answer
42 views

How are physiological reversal potentials (or ion concentrations) of neurons measured?

Patch clamp electrophysiology experiments typically use an intracellular solution that mimics the ionic concentrations of neuronal cytosol. At the same time, the extracellular solution is meant to ...
2
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1answer
72 views

What's the explanation for those shivers/shudders that happen at random times? [closed]

They happen at any time, presenting as a sudden urge to shiver/shudder all at once. It originates in the neck and shoulders, feels like instant gooosebumps then out of total reflex shoulders roll back ...
3
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1answer
64 views

Development and function of spindle neurons

In his book How to Create a Mind author Ray Kurzweil makes some claims about spindle neurons that he provides no source for. Concretely he states that spindle cells: Are Involved in handling ...
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0answers
32 views

What is an extinction test?

In Stolerman & Olufsen (2001) I read the sentence: After drug-appropriate responding with the training mixtures reached 85%, generalisation to ethanol was examined in extinction tests. ...
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0answers
14 views

How do the connections from V1 to V2 form during early development of the human brain?

I am wondering how corticocortical efferents from layer I and II in V1 develop to forward visual information to layer IV in V2. Is there topology preservation in these connections from the beginning ...
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1answer
16 views

Is the thecal sac ectoderm?

The thecal sac, or dural sac, is the membranous sheath of dura mater that surrounds the spinal cord and the cauda equina. The thecal sac contains the cerebrospinal fluid in which the spinal cord '...
3
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1answer
26 views

How can dopamine modulate synaptic strength?

Does dopamine act on G protein coupled receptor, leading to more Ca2+ channels on the postsynaptic knob? Also, how is the specificity of the location (of the brain) that dopamine acts on controlled? ...
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5answers
13k views

Why do the two hemispheres of the brain control the opposite sides of the body?

Why does the left hemisphere control the right and the right hemisphere control the left? I googled it but didn't find a good answer regarding this. Could someone explain? Does this adaptation help ...
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1answer
56 views

Definition of general anesthesia

To quote Goodman & Gilman : An alternative way of defining the anesthetic state is to consider it as a collection of “component” changes in behavior or perception. The components of the ...
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1answer
36 views

Are axons capable of endocytosis?

There is evidence for the uptake of toxic substances like prions from the cell bodies of neurons via endocytosis. There is also evidence for prion deposition in white matter. But I haven't been able ...
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120 views

Why we shiver/tremble/shake while performing some work which requires high accuracy?

Shivering when nervous or anxious is a common thing. But, shivering or trembling sometimes also occurs when we are performing a work which requires high accuracy. In such case, our whole body doesn't ...
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61 views

I get regularly get déjà vu - but I know it's not a memory recall - I always think it's from a dream [closed]

My apologies if this is not the right forum for a neuroscientific/psychological question, especially not one coming from personal experience. Please close/move as appropriate :) Doubtless we're all ...
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2answers
74 views

Metabolic activity postmortem

I read some papers about studies on metabolism in post-mortem tissues in human, but I do not exactly the reason about why our brain continues to have activity after death.
4
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1answer
69 views

Do repetitive movements on EEGs show up as discernible patterns?

Here is a typical EEG reading: If I am connected to an EEG, and am sitting perfectly still, and then begin doing some repetitive motion, say, 10,000 times, will we see discernible patterns emerge ...
4
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1answer
150 views

What are dreams, biologically?

Falling asleep or states of subconsciousness does not stop the mind from making its own fictional images. These seem like sensations just like those received from human eyes. But, how do we define ...
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1answer
230 views

How is color information transmitted from the eye to the brain?

Is color information sent from the eye to the brain frequency-modulated, or are different colors transmitted by different axons? I know that each ganglion cell is connected to multiple photoreceptors....
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1answer
111 views

Criteria for compound action potential thresholds

As opposed to action potential thresholds (which are binary yes/no events), electrophysiological thresholds of compound action potentials are arbitrary. Mostly a certain noise level is picked and when ...
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2answers
179 views

What will happen if we expose the brain to intermittent light?

If a brain is exposed to an intermittent light source, are specific areas going to fire? If yes, which of them? Is there a experimental data about this effect?
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0answers
83 views

What causes the range of severity of neurological deficits in Down's syndrome?

It's known that the severity of symptoms caused by a trisomy 21 varies from individual to individual. Part of the explanation for this range of severity is the finding that 94% of Down's syndrome ...
4
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2answers
156 views

Brain wave and motor movement correlation

I am trying to better understand which brain waves are generated when the motor system (arms, legs, muscles of any kind) are activated. According to Wikipedia, several types (Beta, Gamma, Mu) appear ...
3
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2answers
314 views

Confusion about resting membrane potential and the Na/K pump [duplicate]

To this day, very few people and sources have been able to clear up my confusion about resting membrane potential and how it is maintained. It seems like this is one of those topics that few people ...
3
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3answers
84 views

Resting membrane potential: K+ concentrations and charges on inside and outside of the neuron

According to this site, there is a greater concentration of K+ ions inside the cell than outside. The following screenshot, taken from this website, supports this statement. However, I don't ...
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26 views

Why is the autonomic nervous system divided into parts? [closed]

Why would it be advantageous from an evolutionary perspective to develop parasympathetic and sympathetic systems?
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0answers
56 views

What is the reason for fear induced defecation?

I started to handle mice for my job and noticed that they tend to defecate and/or urinate when they are scared. The fear is induced by me, because I need a long time (due to inexperience) to grab the ...