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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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4 votes
1 answer
470 views

Enigmatic picture of an axon

An image from Terrence Sejnowski's lab is around since at least 2015 when it appeared in an article about hippocampal spine head sizes and only recently (May 2024) in an article about synaptic ...
-1 votes
1 answer
28 views

how can a ganglion be defined as cluster of neuron bodies when it has interneurons?

Let alone the presynaptic button existing there as well, how is a whole interneuron existing there not contradict the definition ?
1 vote
0 answers
24 views

Neuronal reflex circuit

I am having trouble understanding an exam question. I am given a diagram which looks like this: I am having a lot of trouble understanding this diagram since it looks unlike the diagrams usually ...
0 votes
0 answers
44 views

Will diffusible protein aggregates coated in cell-free nucleic acids near a depolarizing neuron's soma diffuse along the axon to synapsing neurons?

Edit in response to feedback in comments requesting specific details, etc.: Will aqueously diffusible protein oligomers and protofibrils coated in cell-free nucleic acids in the aqueous interstitial ...
0 votes
0 answers
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Action Potential [duplicate]

I was wondering what exactly initiates an action potential? I understand that for depolarisation to occur, the membrane potential must first pass through the threshold potential, but what process ...
1 vote
1 answer
69 views

What is a polar plot of relative neural firing

I am taking my PhD qualifying exams on monday, and there is a seemingly simple practice problem that I can't seem to figure out, and I was hoping someone here would have some knowledge, or at least be ...
2 votes
1 answer
96 views

Nernst Equation and Membrane Potential

I am a bit confused on how to use the Nernst equation to determine polarization. I saw in the textbook that if potassium channels were open in a neuron cell, there will be a net diffusion of $\ce{K+}$ ...
0 votes
1 answer
216 views

What is the evidence that women experience a larger cortisol spike than men, when they see domestic clutter?

I'm reading a book "The Organized Mind: Thinking Straight in the Age of Information Overload" by Daniel Levitin. At the beginning of chapter "Organizing our homes" he says that ...
0 votes
1 answer
45 views

Why doesn't treating neurons with a high sodium solution depolarize their membranes?

I am reading a journal paper, and in one of their experiments they treated organotypic hippocampal slice cultures with a high potassium solution to depolarize the neuronal membranes: We found that ...
7 votes
1 answer
1k views

Do color-blind people have more rod cells in their retinae than the normally sighted?

All types of color-blindness are said to be caused by the defect or lack of cone cells in the eyes[1]. Since cone cells sense color[2] and rod cells can only sense light intensity[3], the lack of cone ...
-1 votes
1 answer
89 views

Does communication with new parts of body requires internal changes in brain?

I am not a biological scientist and have low biology knowledges in general, but I want to know some thing. Most of us probably can't even imagine what it feels the sixth finger to be touched. Because ...
3 votes
0 answers
98 views

Is there a biological determinant for right- or left-handedness?

When I was very young, I was sent by parents to examination where I was told both my hands are dominant in the same way. My parents preferred to make my life easier and chose to focus on my right hand ...
0 votes
1 answer
45 views

Can Neurons be connected in Series and will that pattern create huge voltage in human body?

We have learned in Physics that when multiple voltage sources are connected in Series , the resultant voltage becomes the summation of all voltages . Now, my question is - Can Neurons be connected in ...
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0 answers
29 views

Is it true to say neurons like to be stimulated?

I believe I have heard people saying "Neurons like to be stimulated". Although I know stimulating the brain promotes more neurons and connections growth, but does stimulating a neuron ...
4 votes
0 answers
125 views

Does the molecules in nerve cell membrane change 100% during the life of the nerve cell?

In their lifespan nerve cells do not divide and so they stay the same. They do get damaged sometimes and require some maintenance and change their axons a bit. They also require a lot of energy so ...
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0 answers
61 views

Does tetrachromacy affect eye color?

The majority of people have three cones in their eyes, though there are rare cases of some people having 4 cones (tetrachromacy). There is some genetic testing to support evidence of tetrachromacy, as ...
2 votes
1 answer
55 views

Why do V_Na and V_K stay unchanged in Hodgkin-Huxley model?

In the Hodgkin-Huxley model, ionic current $i_\mathrm{Na}$ and $i_\mathrm{K}$ are given by $$ i_\mathrm{Na}=g_\mathrm{Na}(V_\mathrm{m}-V_\mathrm{Na})\\ i_\mathrm{K}=g_\mathrm{K}(V_\mathrm{m}-V_\mathrm{...
0 votes
0 answers
15 views

Proportion of cell layers in the different areas of human cortex

I am looking for any scientific paper or book which could help me find the different proportion of layers across the different areas of the human cortex. I am working on a research project which ...
0 votes
1 answer
28 views

Why is there a negative sign before voltage in the gate variable functions of the Hodgkin-Huxley model?

In Hodgkin and Huxley's articles (1952, J. Physiol.; 1990, Bulletin of Mathematical Biology), the gate variables are formulated as In particular, as $V$ increases, $\alpha_n$ decreases and $\beta_n$ ...
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 ...
0 votes
0 answers
23 views

What are all the possible abnormalities in our body that will result in ataxia?

So I know that ataxia is caused by loss of proprioception.I only know that dorsal column medial leminiscal pathway carries proprioceptive fibre to the cerebellum.So in theory damage to either this ...
2 votes
0 answers
214 views

What are the factors affecting reaction time and/or reflex velocity?

So there was this video of a cat killing a snake: Cat reaction time and another of a bobcat killing a rattlesnake Bobcat kills rattlesnake And then this from wikipedia on sand cats: In the Ténéré, a ...
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?
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 ...
1 vote
1 answer
65 views

Are the lower layers of skin more electrically sensitive as opposed to simply heat sensitive?

Today while surfing I accidentally rubbed the top layer of skin in my fingertips off from friction against the surfboard. I didn't think much of it until later in the day when I was using my laptop. I ...
0 votes
0 answers
22 views

Which co-transmitters are released first?

I understand that a single neuron can release different neurotransmitters depending on the frequency of its stimulation (see https://www.ncbi.nlm.nih.gov/books/NBK10818/). As the frequency of ...
6 votes
2 answers
721 views

Can acetylcholine leak away from the synapse and cause spasms?

I am currently studying Pharmacology and a question came to mind. We know that Acetylcholine is used as a neurotransmitter in the neuromuscular junction, both Sympathetic as Parasympathetic, but as I ...
33 votes
3 answers
36k views

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 ...
0 votes
2 answers
192 views

What is the evidence for cognition being mainly confined to the brain?

We believe that the processes of cognition are mainly confined to the brain. What is the evidence for that? I understand that the brain shows increased oxygen saturation in fMRI scans while thinking ...
0 votes
0 answers
58 views

Confusion regarding the role of the capacitor in the electrical equivalent of a membrane

I am having trouble understanding the electrical equivalent of a cell mebrane as it is shown in this picture taken from Kandel: What I cannot understand is the capacitor in the specific image. Why is ...
3 votes
1 answer
329 views

Why chemical synapses are more common?

Reading into the types of synapses I found out that there are two types of them; electrical and chemical. chemical synapses use neurotransmitters to transmit impulses, are slower than electrical ...
4 votes
2 answers
6k views

How can some animals see ultraviolet or infrared light?

I know that some animals like birds, bees, and fish can see ultraviolet and infrared light. Whether it is to detect flowers that bear nectar, or the urine trails of prey. But what I don't understand ...
1 vote
2 answers
583 views

Do voltage-gated channels in a neuron use ATP

I have a question about action potentials in a neuron. Do voltage-gated sodium and potassium channels use ATP? I mean when they are closed or when they want to open the gate, do they use ATP?
3 votes
2 answers
97 views

electrotonic spread and screening

(In physics.stack I have been suggested to post my question also here.) In the classical theory of passive neurons (where the action potential is not yet excited), the voltage is successfully ...
0 votes
0 answers
26 views

NMDA receptor depolarization

I learnt that two factors for NMDA receptor channels opening are: 1)Binding of glutamate 2)Depolarization of postsynaptic cell (to remove the Mg+2 block) Given that depolarization starts in axon ...
5 votes
2 answers
1k views

Where in the cochlea are frequencies below 200 Hz detected?

I understand that different frequencies are detected in different positions along the cochlea. I'm also aware that the range of human hearing is roughly between 20 Hz and 20 kHz. However, looking at ...
3 votes
1 answer
87 views

Are there internal systems of organisms which acquired the functions which they were not evolved to perform?

In his research on the issue of belief formation Daniel Gilbert (1991. How Mental Systems Believe) claimed that cognition "is an evolutionary outgrowth of [perception]." What he meant is ...
2 votes
3 answers
922 views

Functional unit

What is meant by functional unit of a system? Like when we say that the neuron is the basic unit of neural system, do we mean that all those things that are performed by neural system can be performed ...
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 ...
1 vote
0 answers
31 views

Is there a good protocol for bilateral decortication in rodents?

I was thinking about using bilateral decortication in rodents (preferentially mice) to study the roles of certain brainstem areas in cognitive tasks in the absence of cortex. However almost all ...
0 votes
2 answers
89 views

What happens to the empty space ion pumps create?

Sodium-potassium pumps pump two potassium ions in and three sodium ions out. That means that it creates space for one more ion. Eventually, it's going to be filled. The concentration will be fine, as ...
0 votes
1 answer
380 views

Why isn't the resting membrane potential at equilibrium?

There has been a question asked regarding the purpose of ion pumps, and the main answer was that the resting membrane potential isn't in an equilibrium state, so the potassium keeps flowing out. Other ...
0 votes
1 answer
88 views

Why does the concentration gradient of one ion represent the entire cell in the equilibrium potential of an ion? [closed]

The Nernst equation for the equilibrium potential of an ion(in this case potassium), $$E_{eq,K^+} = \frac{RT}{zF} \ln \frac{[K^+]_{o}}{[K^+]_{i}}$$ includes the ratio of the concentration of that ...
3 votes
1 answer
373 views

Why do larger neurons have less cytoplasmic resistance?

I'm studying neuron electrochemistry rn and my book basically says that the more the cytoplasm impedes the flow of ions, the slower conduction will be, therefore larger neurons will have lower ...
5 votes
0 answers
160 views

Detailed working of the voltage-gated sodium channel

Hodgkin and Huxley formulated the ion currents through the three voltage-gated ion channels Na, K, and L as $$\sum_{k}I_{k}=g_{\rm Na}\,m^{3}h\,(u-E_{\rm Na})+g_{\rm K}\,n^{4}\,(u-E_{\rm K% })+g_{L}\,...
0 votes
1 answer
80 views

How does a neuron change its function, without changing its synaptic connections?

How does a neuron change its characteristics in order to change its function, without changing its connections with the neural networks? Basically, do any organelles change their properties and are ...
4 votes
1 answer
80 views

Ischemia-induced deploarization in excitable cells

I have read in many sources that ischemia-induced depolarization is due to the opening of ATP-sensitive potassium channels and inactivation of Na/K exchangers [1,2]. However, K-atp channels are inward-...
6 votes
1 answer
343 views

How does hypokalemia antagonize lidocaine's effect?

I was reading the lidocaine user's manual for dentistry use and according to it and I quote "Lidocaine in concomitant use with acetazolamide, thiazides and loop acting diuretics. The hypokalemia (...
6 votes
1 answer
399 views

What is the biological limit on hearing resolution?

I sometimes wonder how many different individual musical scales could be perceived by human ears. I define a musical scale as a collection of notes that relate to some fundamental frequency by ...
2 votes
0 answers
38 views

conduction in unmyelinated axons

(Not a specialist here) Several questions touch the voltage propagation along an unmyelinated axon, but I'd like to focus on the following. How fast does the voltage of a sub-threshold perturbation ...

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