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Questions tagged [neuroscience]

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

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33 votes
3 answers
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Why is saltatory conduction in myelinated axons faster than continuous conduction in unmyelinated axons?

How does spacing apart sodium and potassium channels allow the action potential to travel faster down the axon? This is the reason always cited for saltatory conduction and myelination, but my mental ...
user7924's user avatar
  • 333
34 votes
3 answers
4k views

How and where, in the human brain, are memories stored?

Background I am a computer programmer who is fascinated by artificial intelligence and artificial neural networks, and I am becoming more curious about how biological neural networks work. Context &...
Matt Cashatt's user avatar
2 votes
2 answers
847 views

Ambiguity about the relation between membrane potential and concentration gradient in neuron cells

I am stuck in an ambiguity about the equilibrium potentials of neuron cells. The following text is picked up from khanacademy website: In one part it is said that: We'll start out with K at a higher ...
m.taheri's user avatar
  • 121
2 votes
2 answers
626 views

Why does resting potential not become continually more negative?

(Firstly, I know this is similar to other questions, but I have read those answers and they do not really cover this topic). My understanding of resting potential: action potential is not being ...
Ben Hughes's user avatar
38 votes
6 answers
46k 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 ...
lmathl's user avatar
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18 votes
1 answer
564 views

The human brain in numbers I: neurons

Even though knowing the number of neurons in a functional unit or with the same function is not of main importance, it may be interesting to know their orders of magnitude, especially in the human ...
Hans-Peter Stricker's user avatar
13 votes
3 answers
1k views

Long-term-potentiation and memory. Where do we stand?

I was reading the answers to the question: How and where, in the human brain, are memories stored? and, as expected, LTP and LTD came out. Every time I read about LTP/LTD there is always something ...
nico's user avatar
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73 votes
3 answers
16k views

How does the brain's energy consumption depend on mental activity?

What is the impact of mental activity on the energy consumption of the human brain? I am most interested in intellectually demanding tasks (e.g., chess matches, solving a puzzle, taking a difficult ...
Piotr Migdal's user avatar
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43 votes
3 answers
80k views

If the brain has no pain receptors, how come you can get a headache?

I've read many years ago in books, that the brain has no nerves on it, and if someone was touching your brain, you couldn't feel a thing. Just two days before now, I had a very bad migraine, due to a ...
Zerium's user avatar
  • 585
25 votes
2 answers
2k views

How is temperature sensed?

Can anyone summarize the mechanism by which when an object of a given temperature is placed in contact with, say, the skin on a human fingertip, the average speed of the particles of the object is ...
mring's user avatar
  • 1,963
17 votes
3 answers
567 views

Under what conditions do dendritic spines form?

I'm looking for resources or any information about the formation of dendritic spines and synaptogenesis, especially in relation to how new connections are formed on a daily basis. Does the ...
hiddensunset4's user avatar
15 votes
4 answers
9k views

Is there a correlation between total neurons and intelligence?

Thanks for looking. First off, I am not a biologist, just a curious layman, so I apologize in advance if this isn't a "good" question. Please don't downvote me into oblivion. I read today ...
Matt Cashatt's user avatar
9 votes
3 answers
2k views

How do our eyes detect light at different frequencies?

Here is my confusion: we can see colored light of different wavelengths: form red to violet. To my understanding, these stimuli cause a confirmational change in the photoreceptors in our eyes and ...
Confusedbyeverything's user avatar
9 votes
1 answer
3k 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 ...
hello all's user avatar
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8 votes
3 answers
372 views

Is the ratio Brain Mass/Total Mass still considered a valid indicator of intelligence?

I was reading this(1) and it led me back to ask a very basic question (I'm not a neuroscientist). All the way back to undergrad anthropology and neuroscience courses I remember being taught the ...
Atl LED's user avatar
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8 votes
1 answer
5k views

Why does an electric shock contract the muscle?

From what I understand, the electrical impulse in our nerve cells is not made of electrons, but of ions that move from different environments with different concentrations, which is totally not ...
gigie's user avatar
  • 89
6 votes
1 answer
920 views

How does a change in the potential across a neuron's membrane get turned into a signal that is sent down the axon?

I understand How a signal is propagated down the axon. How the membrane potential of a neuron changes during the course of it's "firing". But I don't understand how physically the change in the ...
Stan Shunpike's user avatar
5 votes
1 answer
444 views

What is the mechanism by which myelination reduces the capacitance of the axon membrane?

There are two mechanisms that have been proposed to me. 1) Layering of Schwann cell membrane with conducting fluid between the layers is analogous to several capacitors in series. Since capacitance ...
D.J. Lawson's user avatar
4 votes
3 answers
1k views

Mechanical cause of loss of consciousness

Consciousness is an electrical and chemical interaction in the brain, caused by neurons firing and chemical interactions. How does a mechanical "force" cause this to stop working? i.e. How does a ...
Laurence's user avatar
  • 115
64 votes
4 answers
9k views

Are there organisms with fewer than 1000 neurons?

I'm developing neural networks comprised of just 3 to 10 layers of virtual neurons and I'm curious to know if there are any insect brains out there with fewer than a thousand neurons? Are there any ...
J.Todd's user avatar
  • 1,891
43 votes
2 answers
4k views

Can brain cells move?

I was discussing this with my brother. I'm pretty sure I read somewhere that they can move. Thanks EDIT: By movement I mean long distance migration (preferably within the brain only).
DLV's user avatar
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40 votes
2 answers
8k views

What actually happens when my leg 'falls asleep'?

Most people have experienced the temporary loss of feeling and tingling in their leg resulting from sitting in an abnormal position for a short while. Usually you get a loss of feeling in your leg ...
Gordon Gustafson's user avatar
25 votes
2 answers
38k views

How do the brain and nerves create electrical pulses?

The information between the brain and peripheral nerves is sent via electrical pulses or signals, How then does a non-metallic human cell manage to conduct an electrical signal?
johnny1bucket's user avatar
24 votes
9 answers
23k views

Why have humans evolved much more quickly than other animals?

Humans have, in a relatively short amount of time, evolved from apes on the African plains to upright brainiacs with nukes, computers, and space travel. Meanwhile, a lion is still a lion and a ...
Matt Cashatt's user avatar
22 votes
3 answers
63k views

Why can't neurons undergo cell division?

Many cells in the human body can divide and reproduce, making healing possible. Neurons, however, cannot reproduce, which makes diseases affecting the brain particularly crippling. Why can't neurons ...
HDE 226868's user avatar
  • 1,405
20 votes
1 answer
635 views

Why are fearful stimuli more powerful at night?

For example, horror movies appear to be scarier when viewed at night than during broad day light. Does light have any role in this phenomenon? Are there changes in hormones at night versus during ...
Mesentery's user avatar
  • 3,293
15 votes
2 answers
2k views

Are there neurons that can sense light shining in your ears?

I know someone who bought earphones that shine light in you ears. According to what he was told, there are neurons that sense light and then make you feel wide awake when activated, which seemed like ...
Ultimate Gobblement's user avatar
14 votes
2 answers
3k views

How does a neuron change as you learn?

I am currently taking a course called "Introduction to Machine Learning with ENCOG 3", and I have a question about how well the Artificial Intelligence (AI) algorithm for a "neural network" ...
Greg Thatcher's user avatar
11 votes
2 answers
4k views

How do neurons form new connections in brain plasticity?

I've been reading about brain plasticity and how the brain can "rewire" itself. One of the things that is not clear to me - how neurons can establish new connections. Does this rewiring mean that ...
Alex Stone's user avatar
  • 6,515
11 votes
2 answers
1k views

How are neurons / synapses "biased"?

I'm trying to see if I understand this correctly. I've read the question Can the human brain be reduced to a binary system? and one of the answers explains: While action potentials are usually ...
J.Todd's user avatar
  • 1,891
10 votes
2 answers
3k views

How does an inhibitory synapse communicate to the cell body of a neuron?

I picture a neuron as having multiple trees of dendrites attached to the cell body with a single axon leaving the cell body. I believe the cell body near the axon root makes the decision to fire or ...
FrankH's user avatar
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10 votes
2 answers
27k views

How is membrane capacitance related to the increased speed of saltatory conduction?

Here is the original question which inspired my question. As explained by the answers there, the reason saltatory conduction in myelinated neurons is faster than non-myelinated conduction is because ...
stochastic13's user avatar
  • 4,689
9 votes
2 answers
8k views

Do ants feel pain?

I have watched video on youtube where guy pours molten aluminium into fire ant colony to make casing. In the comments below there's huge discussion on is that a right thing to do. I am on the side ...
Matas Vaitkevicius's user avatar
9 votes
1 answer
1k views

What causes Paresthesia (Pins and Needles) at a cellular level?

I've looked it up in plenty of places like the Wikipedia page and such, and it is clear that the most common cause of Paresthesia is either a fair amount of pressure on a specific patch of skin ...
Ethan's user avatar
  • 193
8 votes
2 answers
3k views

How does the brain know where a signal came from? What is the addressing system

I am an electronic engineer so I am thinking about this from an electronics outlook. How does the addressing system work, As I see it, the nervous system is small parallel branches attached to larger ...
Shasam's user avatar
  • 83
8 votes
2 answers
779 views

How does a pinched nerve cause pain (at the molecular level)?

Is this due to pressure differentials in the surrounding tissue? (Is it possible to have a pinched nerve without compression of the surrounding tissues, and does this cause pain?) What are the ...
blep's user avatar
  • 2,824
8 votes
3 answers
2k views

Advantage of opponent color?

Opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner (source). What is ...
Abalfazl Moridi's user avatar
7 votes
1 answer
147 views

Cortical projections from layers 2/3 back to 4?

As all excititory neurons in layer 4 are stellate - they have no apical dendrites that could project to layers 2/3. However, I have seen some diagrams showing axonal projections from layers 2/3 back ...
sebjwallace's user avatar
7 votes
1 answer
203 views

Bugs' love for light

Do bugs love light bulbs because they resemble the stars or is it the sun? How do they sense the bulb? What is the purpose of this "brightophilia" that has evolved in insects?
AWE's user avatar
  • 179
7 votes
2 answers
2k views

Can a single axon propagate multiple simultaneous action potentials?

I have not been able to locate any research that indicates whether a single axon of a neuron or nerve cell can conduct multiple simultaneous (i.e. spatially separate) action potentials. I am aware ...
watsonic's user avatar
  • 171
6 votes
1 answer
2k views

Why do larger diameter myelinated axons have greater conduction velocities than small diameter myelinated axons?

A canonical statement I have frequently read is that "large diameter axons conduct action potentials at faster velocities than small diameter axons". After recently learning the effect of increased ...
S.C.'s user avatar
  • 375
6 votes
2 answers
15k views

Can the human eye distinguish colors in the periphery?

In the back of my mind I have the idea that human eyes can't notice the color of objects in the far periphery, and that any subjective perception of colors is done by the brain that tries to fill in ...
Christian's user avatar
  • 2,616
6 votes
2 answers
1k views

Inductance in cell

In an animal cell, especially neuron and in particular its axon, while there is electrical resistance and capacitance mechanism in the cell, which play essential roles in the cable theory model of ...
Hans's user avatar
  • 486
6 votes
2 answers
480 views

Do smaller intelligent animals have a higher neuron density to account for their seeming intelligence? Otherwise, what?

It seems like there's a lot of very small animals that have a much higher intelligence than what you would expect if you linearly projected intelligence as a function of brain size. There's ravens, ...
RayOfHope's user avatar
  • 557
4 votes
1 answer
751 views

If people with colorblindness lack one type of cone cells, shouldn't they be unable to recognize one particular color?

The 3 types of cone cells in normal humans allow them to view 3 types of colors and any color made from mixing and matching those 3. So, 2 types of cone cells should only allow to view just 2 types ...
laggingreflex's user avatar
4 votes
1 answer
3k views

Saltatory conduction of nerve impulses

I am aware about some basics of saltatory conduction of nerve impulses. I know that the nerve impulses (ion flow and the depolarization) are transferred from node to node in myelinated nerve fibers. ...
user avatar
4 votes
2 answers
53k views

What are the functions and differences between axons and dendrites?

My textbook doesn't do a very good job of pointing out what the differences between the two are. It basically mentions axons only in the same breath as the synapse (that synapses are the endings/tips ...
Lesbihonest's user avatar
4 votes
1 answer
245 views

Why do we yawn?

I've read a new study which suggests that yawning may help you keep a cool head. Also, the findings might hold some hope for sufferers of insomnia, migraines, and even epilepsy. Is there any ...
Ioanna's user avatar
  • 141
4 votes
1 answer
3k views

If nerve consists of many axons, where are then their soma located?

This question has haunted me for two years. Wikipedia mentions : A nerve is an enclosed, cable-like bundle of axons (the long, slender projections of neurons) in the peripheral nervous system. A ...
user avatar
4 votes
1 answer
319 views

Why is peripheral vision not bleached by daylight?

In daylight, rods are known to be bleached: we have to wait some time after going into darkness before scotopic vision becomes effective. But, as I understand, peripheral vision is also mostly due to ...
Ruslan's user avatar
  • 425