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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To what extent does the distribution of nerual transmiters in the brain vary human to human?

Suppose $x$ is a position in the brain, and $n_i(x)$ is the density of neuro recepter $i$ around that point. Any given human will have some distribution of neruo recepters $n_i(x)$ through out there ...
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What happens in a nerve cell when a thought is generated?

I know basic nerve physiology of impulse conduction and transmission, but I don't know what actually happens in a nerve cell when a thought is generated. When a external stimulus (like tactile ...
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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 ...
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174 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 ...
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276 views

Why doesn't oligodendrocyte produce neurilemma

I was searching literature related to neurilemma and oligodendrocyte and came across these lines from WP (Neurilemma) Oligodendrocytes do not have neurilemma because excess cytoplasm is directed ...
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Once neurotransmitters bind to its receptors, how does the post synaptic neuron “know” when to start a new action potential?

My textbook seems to gloss over this subject. Once the post-synaptic receptors are activated, do they cause particular ion channels to open, letting positive charge into the cell and inching the ...
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170 views

What happens in a brain of a person suffering with apathy?

According to this article Apathy is a profound loss of motivation not attributed to decreased level of consciousness, cognitive impairment, or emotional distress. Apathy refers to a set of ...
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Flow diversion for cerebral aneurysms or stabilizing the hemodynamics?

I'm doing research of flow diverter for cerebral aneurysms applications and I'm wondering the reason behind stent placement underneath of cerebral aneurysms is to divert the flow or stabilize the ...
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How to determine if the amount of manganese chloride will change neural resting potential

If I am treating an organism in MnCl2 dissolved in water, how do I determine if the amount of Cl (in MnCl2) will change the neural resting potential Oor if it will influence motoneurons?
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loops in neuron synapses

If we see at the connectome of c.elegans, it is easy to find "loops", in the simplest case, a neuron that synapses to another and this one backward to the first. By example, neuron RIAR has 13 ...
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What is the mechanism behind the F-Wave?

Can someone explain the actual mechanism behind the F-wave? Is it really different from a H-reflex response or does it just have another name for historical reasons? The H-reflex (Hoffmann's reflex) ...
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1answer
113 views

Volley theory and sound amplitude/power

Assume a pure tone (single frequency) is listen, lets say 2 kHz. If I understand correctly the temporal theory (aka timing theory), in a cochlea neuron the action potentials create a signal that will ...
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Neuron connectivity- how are they connected physically

If Neurons are only connected through synapse and there is no physical connection, how are they just suspended in brain layers?
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What is the signal conversion from hair cells to cochlear nerve cells?

If I understood correctly, inner hair cells generates a graded potential (receptor potential), this potential maps the stereocilia deflection. On the other hand, the cochlear nerve cells transmit ...
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Can a brain dead person recover?

Many times I have heard someone having to pull the plug because the patient was declared brain dead before the body healed fully? Why do they pull the plug without first waiting till the body/brain ...
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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 ...
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341 views

How do you check how many cones you have in your eye?

Following my previous question: What color does the other cone in Tetrachromacy correspond to? People with normal color vision posses 3 cones in their eye. But there are some rare cases when people ...
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How does a neuron know to which one of the next neurons to pass the signal

Looking into how neural networks are build in the brain, here are a couple of facts followed by some questions: The neuron receives the signal through its dendrites and passes it to the terminal at ...
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Specific Neurons that Require Glucose

I've been doing a bit of armchair biology lately, and have been interested in the metabolic flexibility of neurons. My understanding is that, besides glucose, many neurons can metabolize lactic acid ...
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How is ATP converted to adenosine?

I am familiar with adenosine diphosphate (ADP) and adenosine triphosphate (ATP), how one relates to the other, and how each is formed in cellular respiration and photosynthesis, but I am confused as ...
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The information carried by nerve signals

Action potentials carry nerve signals in individual neurons and somehow encode information. My question is if it is possible to read that information carried by the nerve signal and feed it into a ...
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Scaling of Ca2+/biochemical signals with dendritic spine size?

I am looking for references that discuss the scaling of biochemical signals in dendritic spines with spine size/synaptic strength. A recent paper (Walker et al. 2017) reports attenuation of NMDA ...
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1answer
415 views

What is the purpose of the viscous gel in the Pacinian corpuscle?

I have read that 'when the stimulus (in this case pressure) is constantly applied, the gel repositions itself to prevent the formation of an action potential'. I don't really understand what this ...
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Why do we feel numbness and an electric sensation in our legs after standing for too long?

We have all felt that numbness while standing immobile for a while.It gets difficult to walk.It can also happen if we are just putting some pressure on our legs Why does this happen? I'd like to ...
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What repairs faster when injured: white matter or grey matter?

This was the exact wording of a test question given by my biology teacher and she said that white matter would repair faster, because there is a myelin sheath to protect the cells. Do you agree with ...
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What color does the other cone in Tetrachromacy correspond to?

Human with normal vision possesses 3 cones, which correspond to blue (S), green (M) and red (L). What about tetrachromacy, where people have 4 cones in their retinae? What is the fourth cone exactly, ...
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Pitch perception - why is the missing fundamental not directly detected in the cochlea?

I'm learning about pitch perception, and learned about the case of the missing fundamental. In the main image in that wikipedia page, it seems like the bottom graph, with the fundamental frequency ...
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Are there any known rules that neurons always follow while transmitting/receiving signals?

I'm new to neurobiology so I don't know much about it. However, I have worked on artificial neural networks. Man-made AI networks all follow a handful of simple rules. I was wondering if biological ...
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Why do some reflex actions involve interneurons, but some don't?

According to what I know, the reflex arc of knee jerk reflex doesn't involve interneuron, but other reflex action (e.g. removing your hand when touching hot things) do involve interneurons. Why is ...
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What is the distribution of the major ions across a neuronal membrane for a human neuron? [closed]

I have searched for the ion distributions across the membrane of human neurons on the internet but almost all the information refers to the giant axon of the squid. Could anyone give me the ion ...
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How are presynaptic burst firing signals transmitted post-synaptically?

Neurons can exhibit burst firing and this presynaptic process basically results in a flurry of action potentials being fired in a short time window. I'm, however, wondering how these signals are ...
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1answer
265 views

What photoreceptors are necessary to permit infrared vision?

Humans have red green and blue photoreceptors allowing them to sense colours in the spectrum of about 400-700nm. Certain proteins allow for the extending of wavelength range in the RGB receptors, this ...
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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 ...
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1answer
343 views

Question about the threshold potential

I am a student of Physiology, and I have ended up a bit confused after what I've read today regarding events during a threshold potential. So, while cells are in their resting membrane potential, the ...
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Is olfactory input processed by the thalamus?

Is olfactory input processed by the thalamus? I know olfaction is the only sense that can bypass the thalamus, but are there cases where the input can project to the thalamus?
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Is the masking effect of sound related to action potentials or to mechanical aspects of hearing?

I am an applied mathematics / signal processing engineer who wants to learn more and I have a question that has been bugging me for some time. It is known in audio coding circles that human hearing is ...
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What is the physiological mechanism for getting unconscious after a punch to the head? [duplicate]

It is the everyday life in boxing: One boxer gets a smack in the head, cannot do anything for many seconds and then: Victory of his opponent due to a Knockout! What is the reason for losing ...
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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 ...
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Do axonal conduction delays have a function?

I'm reading about mathematical models of biological neural networks, which can be grouped into two categories: The model accounts for the fact that a signal takes time to travel from the excitatory ...
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How outside signals creates different chemical composition in the brain? [closed]

Scenario A: I am walking down the street and my phone rings. I answer and I am told that my ticket that I registered last week was lucky and I won million EUR. Scenario B: I am walking down the ...
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Dopamine involvement in pleasure

There are some psychologists who believe that dopamine is not released during pleasurable activities but before them; my understanding is that a little dopamine is released pre-reward in order to ...
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458 views

What is the exact frequency of Delta brain waves during Slow Wave NREM Sleep?

I saw a TED talk about researchers playing pulsating pink noise while a test subject is in Stage 3 Non-REM / Slow Wave / Deep sleep and observing an increase in Delta wave EEG activity. This seems to ...
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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}\,...
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Causes of the stochastic behaviour of voltage-gated ion channels

I came up with the following electro-mechanical model of a voltage-gated ion channel, resp. of its voltage sensor as described here and here. The voltage sensor is a bistable system with two local ...
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Why are there exactly 207 morpho-electrical types of neurons?

I'm taking an introductory neuroscience course online, and it mentions that of the 55 morphological types and the 11 electrical types, there are 207 morpho-electrical types. How does this work? 55 ...
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396 views

Visual phototransduction, neurons depolarization when no light: why?

While reading into visual phototransduction I was surprised to learn that photoreceptor cells are actually depolarized when there is NO excitation (no light, i.e. when you see nothing, black) and ...
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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 ...
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Electrical field stimulation of neurons: what are commonly used stimulation protocols and which are physiological?

I am doing a labproject with primary mouse nerve cultures (hippocampus and midbrain) and part of the experiments involve performing electrical field stimulation on these neurons. For now we have ...
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What gives nerves their silver colour?

I always thought the silver colour specific to nerves was due to the myelin sheaths, but I've observed that unmyelinated C fibres display that same silvery appearance. Where does this colour come from?...