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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104
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3answers
24k views

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, ...
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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 ...
65
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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 ...
61
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4answers
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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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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 ...
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3answers
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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 ...
28
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5answers
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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 ...
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7answers
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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 ...
25
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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 ...
24
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1answer
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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?
23
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1answer
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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 ...
20
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1answer
551 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 ...
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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 ...
15
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1answer
6k 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 ...
15
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1answer
780 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 ...
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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 ...
14
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2answers
498 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", ...
14
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2answers
919 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 ...
14
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2answers
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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" ...
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2answers
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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 ...
13
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1answer
6k 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 ...
12
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3answers
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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. ...
12
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2answers
183 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 ...
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3answers
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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 ...
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2answers
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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. ...
10
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1answer
761 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 ...
10
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2answers
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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?
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1answer
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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 ...
10
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1answer
372 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 ...
9
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1answer
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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 ...
9
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2answers
838 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 ...
9
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2answers
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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....
9
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1answer
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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 ...
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2answers
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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 ...
9
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1answer
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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 ...
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3answers
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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 ...
8
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3answers
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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 ...
8
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2answers
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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 ...
8
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1answer
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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 ...
8
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1answer
10k 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? ...
8
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1answer
268 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?
8
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2answers
493 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 (...
8
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2answers
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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 ...
8
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1answer
293 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 ...
8
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1answer
229 views

How well does it actually work to surgically reroute the optical nerve?

Two publications, Roe et al, 1992[1] and Metin & Frost, 1989[2], describe results pertaining to the ability of a region of cortex to process information from a different sensory mode than the one ...
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3answers
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What is the science behind the inaccurate perception of colors?

If I go into a green room (all walls are semitransparent and green) and spend some time - around 10+ min - in there, when I come out all my eyes see is white as pink. I see no (or very few other) ...
7
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2answers
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Is NMDA produced in the body?

On the wiki page for NMDA it says that NMDA is a synthetic substance that mimics glutamate. So why does the body not use glutamate instead of NMDA? Also how is it possible that our body can produce ...
7
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3answers
384 views

Do self-exciting neurons exist?

I have two questions concerning self-exciting neurons in the brain. Have directly self-exciting neurons been oberved, i.e. neurons with an axon terminal building a synapse with one of its own ...
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1answer
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What is the actual speed of nerve impulses in humans?

For an undergrad assignment I read a biology paper that mentioned the speed of nerve imuplses to be 440 km/h in myelinated fibers. However, our biology teacher told us that this reported conduction ...
7
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1answer
650 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....