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Questions tagged [neurophysiology]

The study of the physiology of the nervous system, with emphasis on transcellular communication, and cellular and molecular processes involved in neural communication.

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Are male and female brains physically different from birth?

Male and female brains are wired differently according to this article: Maps of neural circuitry showed that on average women's brains were highly connected across the left and right hemispheres, ...
Pablo's user avatar
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83 votes
3 answers
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Is there an RGB equivalent for smells?

Millions of colors in the visible spectrum can be generated by mixing red, green and blue - the RGB color system. Is there a basic set of smells that, when mixed, can yield all, or nearly all ...
Spartacus9's user avatar
71 votes
2 answers
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What is the evolutionary advantage of red-green color blindness?

Red-green colorblindness seems to make it harder for a hunter-gatherer to see whether a fruit is ripe and thus worth picking. Is there a reason why selection hasn't completely removed red-green ...
Christian's user avatar
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64 votes
4 answers
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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 ...
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36 votes
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Is C. elegans always observed with precisely 302 neurons? Are there ever individual viable exceptions?

This answer mentions that the C. elegans hermaphrodite has exactly 302 distinct neurons. This has made it a very effective model for a variety of types of biological research, including neurology and ...
uhoh's user avatar
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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
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31 votes
3 answers
9k views

Can humans ever directly see a few photons at a time? Can a human see a single photon?

I am not asking the following question: Can humans ever see a photon in the same way we see a chair? My question is: Can a human retina respond to a single photon? If so, how does this happen and why ...
Daniel Mera's user avatar
28 votes
5 answers
10k views

What are the advantages of forgetting?

How forgetting things is helpful for the brain or the human body biologically? This web page After some moment of being rude, selfish, or weak, either we are able to put it behind us, or the person ...
Mesentery's user avatar
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25 votes
7 answers
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Why can't we see in low light if staring long enough?

For me it seems reasonable that if I kept my gaze on a fixed point in a room with low light, a progressively brighter and better picture would appear before my eyes, just like a camera can see in the ...
filip's user avatar
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24 votes
1 answer
35k views

Why does my room suddenly look 'reddish'? My eyes seem to adapt to color

To get the context of this question clear, I would like you to walk through some parts of my house. We'll start with one of my rooms as it appears normally - As evident, this part of my house has a ...
sarthak-ag's user avatar
24 votes
1 answer
33k views

Why do adults lose hearing at high frequencies?

Children and teens can hear high pitched sounds that adults can't hear anymore. Why do adults lose high-frequency hearing?
ZZZ's user avatar
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20 votes
1 answer
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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
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18 votes
1 answer
3k views

Why is loud music much louder after pausing and resuming it?

If I pause a sufficiently loud song (in headphones) for several seconds, then resume it, I perceive it as deafeningly loud, even painfully. Yet, if I first lower the volume, resume, and then gradually ...
OverLordGoldDragon's user avatar
15 votes
2 answers
2k views

How to make a fake auditory signal?

My question is about making fake auditory signals. The ear collects sounds from the environment, which are transformed into a neural signal by the hair cells in the inner ear. This signal is sent ...
Nimda's user avatar
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15 votes
1 answer
8k views

Why do we go blind for a few seconds after switching off the light?

At night, when I switch off the lights, I always seem to go blind for a while. The room becomes pitch black and I am unable to see anything. After a while, however, my vision slowly recovers and I ...
علی آفاق's user avatar
15 votes
2 answers
628 views

Is our color vision calibrated to sky, vegetation, and blood?

Our color vision is based on three types of receptors (cones) which are sensitive to three distinct locations on the spectrum: 420–440 nm, 534–555 nm, and 564–580 nm. We label them "red", "green", ...
SlowMagic's user avatar
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1 answer
812 views

Unilateral damage to vagus nerve

Context: The vagus nerves supply the neck viscera, heart, lungs and gastrointestinal tract. They join around the oesophagus to form the oesophageal plexus. Question: Would damage to one vagus nerve ...
Hernandez's user avatar
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14 votes
4 answers
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Is it possible to feel pain in some part of a body, but the pain "feeling" is introduced somewhere else?

Is it possible to feel pain in some part of a body, but that the cause of the pain is situated elsewhere in the body? For example, somebody feels pain in his toe, but it turns out that this pain is ...
scdmb's user avatar
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14 votes
2 answers
2k views

How can action potentials be generated through thoughts?

I think I understand how a signal is transferred from neuron to neuron (from How do the brain and nerves create electrical pulses?). My question, however, is not about the standard textbook material ...
CDB's user avatar
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14 votes
2 answers
1k views

How do neurons find each other?

Neurons form complicated networks in brains, but their connections can't be random (at least not entirely). Brains function similarly among all members of individual species, and that functionality is ...
CircleSquared'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
13 votes
1 answer
3k views

Have elephants (or any species other than humans) been known to cover their dead?

I was just reading this blog on HarperCollins website about 5 animals that grieve. Of elephants, the following claim is made: They bury their dead and pay tribute to the bodies and to the bones. [my ...
Curious Layman's user avatar
13 votes
1 answer
7k views

Why do antidepressants have a delayed onset of action?

Why do antidepressants take so long to reach efficacy? I've read of theories about it perhaps being due to the strength of negative feedback via serotonergic and adrenergic autoreceptors during the ...
Josh Pinto's user avatar
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12 votes
3 answers
8k views

Do spinal cord reflexes (such as the knee-jerk reflex) continue to function under general anaesthesia?

The knee-jerk reflex (patellar reflex) is an example of a stretch reflex (myotatic reflex). Stretch reflexes are monosynaptic reflexes happening in the spinal cord without involvement of the brain. ...
amoeba's user avatar
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12 votes
1 answer
809 views

How does pressure travel through the cochlea exactly?

I cannot find this answer anywhere. What I do know is that the stapes pounds on the round window of the cochlea and this causes the fluid to move inside the cochlea itself, which has the three ...
user525966's user avatar
12 votes
2 answers
248 views

Do ectotherms think slower when they are cold?

Animals near the ectotherm side of the endotherm-ectotherm spectrum rely on external heat sources to regulate their body temperature. When they are cold, overal enzyme activity and metabolic rate is ...
mart's user avatar
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11 votes
3 answers
4k views

Does a neuron ever generate an action potential without stimuli?

Most accounts I read involving action potentials and synapses and the like tend to focus mostly on the action potential as a mere automatic reaction to another similar event happening upstream. From ...
Joebevo's user avatar
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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
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11 votes
1 answer
19k views

Why are potassium channels slower than sodium channels?

I am relatively new in the subject of biology. I have a strong mathematical background and in order to get into the field of computational neuroscience, I am trying to get some biological background. ...
user135172's user avatar
11 votes
1 answer
909 views

Purpose of K+ channels in action potential

I understand that they serve to repolarize the neuron after the Na+ influx. What I don't understand is why this is important. Meaning, let's say all the K+ channels disappeared. So now the ...
Jo.P's user avatar
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10 votes
1 answer
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Why does a light object appear lighter in your peripheral vision when it's dark?

So, I am not sure I can reproduce it via images, but the steps are: 1) At night, open a window and have a look at the surface of the earth 2) Suppose there's an object that reflects a tiny amount of ...
knitevision's user avatar
10 votes
2 answers
9k views

Why can't our eyes smoothly transition from side to side without focusing on a moving object?

Why are we not able to slowly and smoothly look from side to side, or up and down in a single and smooth transition, given that we are able to do this if our eyes are focused on a moving object?
Programmer's user avatar
10 votes
1 answer
1k views

What is the mechanism behind tinnitus?

I seem to have come across two contrasting explanations for tinnitus induced by loud noises- i.e. damage to the hair cells in the cochlea. On the one hand, I have read that damage to the hair cells ...
Meep's user avatar
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10 votes
1 answer
14k views

Why can action potentials not be initiated at dendrites?

Why are action potentials not initiated at dendrites, although dendrites are the first to receive input from the presynaptic cell? In fact, excitatory postsynaptic potentials (EPSPs) at the dendrites ...
Curious's user avatar
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10 votes
1 answer
469 views

Does the nervous system have "routers"?

Does the peripheral nervous system have a system of routers that decide where a message is meant to go based on some kind of address, or does a signal from the brain follow a single, unbroken chain of ...
Raiden Worley's user avatar
9 votes
1 answer
16k views

Are sensory receptors neurons?

Background There are many receptor types in the body, with various functions and various mechanisms of transduction. Receptor cells are considered to be part of the peripheral nervous system, as they ...
AliceD's user avatar
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9 votes
2 answers
2k views

Are unilaterally deaf people able to determine where sound comes from?

My question is on people deafened in one ear, but normal hearing in the other. Time and level differences between the two ears are only part of how the human body can localize the source of the sound....
Fofole's user avatar
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9 votes
1 answer
1k views

Single long axon vs serial neurons

Based on the comments in this post and also this chat. For discussions and speculations please comment in the chat. The basic question is what is the advantage of having a single long axon such as ...
WYSIWYG's user avatar
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9 votes
1 answer
12k views

Why is the human ear most sensitive to 4000 Hz tones?

Human hearing sensitivity is dependent on frequency, which can be visualized by equal-loudness (iso-loudness) contour plots. An example is given below (Taken from here). This plot shows that a tone ...
Arturo don Juan's user avatar
9 votes
2 answers
2k views

What is the latency between paired neuronal responses in the brain?

Is there any data on how long it takes for signals to propagate from one neuron to its neighbors in complex networks, such as the brain (particularly the neo-cortex)? If not, is there any reasonable ...
back2dos's user avatar
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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
8 votes
1 answer
4k views

If tinnitus is, in many cases, caused by damaged ear hair cells, couldn't it be solved by a mini cochlear implant that sends a constant signal?

If my understanding is correct, tinnitus is in most cases caused by damage to the inner ear hair cells, especially on the basal parts of the cochlea, which correspond to high frequencies. So, for ...
MaiaVictor's user avatar
8 votes
3 answers
6k views

Are there animal species that sense infrared light with their eyes?

I asked a question earlier today about birds with infrared vision but this time I am asking about animals in general. I know that many snakes have receptors between their eyes and their snout that ...
Semper Ambroscus's user avatar
8 votes
2 answers
11k views

Why do I still see a bright light after looking directly at it?

When you look directly at a bright light, maybe accidentally when looking at the sun, the shape of the image may persistently be perceived even after you look away. Does this image persistence have ...
Beastly Gerbil's user avatar
8 votes
1 answer
17k views

How precisely can we sense temperature differences?

We have thermoreceptors, thus we can sense temperature (both warm and cold). I'm interested in the sensitivity of our thermoreceptors - What is the smallest temperature difference that we can sense? ...
Nandor Poka's user avatar
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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
8 votes
1 answer
330 views

Can brain damage caused by physical injury affect the social behaviour of a person?

Can a physical injury to the brain, resulting from an accident, and not the result of a diagnosed mental illness, affect a person's social behavior?
Snazzy Sanoj's user avatar
8 votes
2 answers
567 views

What does pain look like in wave form?

I am interested in understanding what "pain" and "hot/cold" look like, as far as waves signatures (signal processing) go. My general understanding of how pain (nociceptive pathways) and hot/cold (...
smeeb's user avatar
  • 639
8 votes
3 answers
2k views

Why don't we hear ultrasonic sounds as aliased versions of the original signals?

The upper limit of hearing is approximately 15 kHz, dependent on age and other factors. According to the principles of digital signal-processing, such an upper limit would mean that the auditory ...
Bzrs's user avatar
  • 223
8 votes
1 answer
369 views

Why don't electric eels shock themselves?

Why do electric eels not stun or pain themselves when they discharge their high voltage shocks? While it is known that they use those high voltage shocks to track their prey (as discovered by my ...
Ben Perlin's user avatar

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