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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What causes the depolarization before Na+ gated channels open? [duplicate]

My book says: "When the membrane potential becomes less negative than during the resting state, rising from −90 millivolts toward zero, it finally reaches a voltage—usually somewhere between −70 and −...
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What does myelin insulate against, exactly?

I am aware of the saltatory conduction model, nodes of Ranvier and all that, and that myelin lets electrical signals "jump". What does not add up to me entirely is what the myelin sheath insulates ...
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Why are eyes more sensitive to flicker in periphery — contradictory answers

In terms of the perception of flickering by CRT monitors, This answer suggests that peripheral vision has faster response and is thus more sensitive to flicker due to being provided by rod cells. ...
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What does microglia process length tell us?

I'm reading a study investigating traumatic brain injury and alcohol consumption and the researchers measured microglia process length as an indicator of brain damage. I was wondering what that would ...
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A question concerning the strength of synapses

Synaptic strength can be defined »as the average amount of current or voltage excursion produced in the postsynaptic neuron by an action potential in the presynaptic neuron« Synaptic strengths and ...
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Are there nuclei with “real” interneurons?

In Kandel's "Principles of Neural Sciences" in the chapter about the anatomical organization of the brain one reads (p. 323, 4th ed.): »Although a variety of [relay] neurons are involved at each ...
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How sharp are the borders between Brodmann areas?

How does the border between two Brodmann areas look like in Nissl stains? How large is the transition zone where one cannot tell to which of the two areas a neuron belongs to? How many neurons are ...
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Long-term potentiations that last for a lifetime

One reads more often than not that long-term potentiation has been reported to last for as long as several weeks LTP is persistent, lasting from several minutes to many months and most sources seem ...
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Which role do dendritic spikes play in long-term potentation?

In the Wikipedia article on long-term potentiation one reads: »When weak stimuli are applied to many pathways that converge on a single patch of postsynaptic membrane, the individual postsynaptic ...
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Normal surplus of neurotransmitters and the need for retrograde signaling

Having learned something about retrograde signaling I wonder why it is so hard to observe and to decide whether presynaptic potentiation actually takes place in the course of long term potentiation (...
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Ion-gated ion channels

Today I've heard for the first time of calcium-gated ion channels but find it hard to get an idea how they work, where they are located, and which role they play. I assume calcium-gated ion channels ...
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Differences between neurotransmitters and neuromodulators

According to the Wikipedia article on neuromodulation a neuromodulator can be conceptualized as a neurotransmitter that is not reabsorbed by the pre-synaptic neuron or broken down into a ...
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Typical firing patterns of neurons in the default mode network in resting state

Inspired by the Wikipedia article on the default mode network where I read: Hans Berger, the inventor of the electroencephalogram, was the first to propose the idea that the brain is constantly ...
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Functional roles of firing patterns

Eugene Izhikevich reports – e.g. here – a plethora of neural firing patterns: My question is two-fold: Is there an overview which types of neurons are capable of (and typically exhibit) ...
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Neuron stimulation experiments

Has anyone extracted a class of neurons (or a connected set of neurons) and stimulated them electrically to get an understanding of their behavior? If so, could someone point me to papers along these ...
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Vision: what is the difference between on-off ganglion cells and lateral inhibition?

Is 'lateral inhibition' just a term for the biological basis of the functioning of the on-center (or off-center) ganglion cells? Or do these terms describe separate processes?
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Is it possible to simulate tetrachromatic vision in a trichromat?

Suppose we are able to stimulate the whole matrix of cones of a human retina, targeting each cone individually¹. Normally we would project an image in the LMS color space onto the cones, in such a way ...
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Physiology of hyperpolarization

In my textbook, it is stated that after the closure of potassium voltage-gated channels and during hyperpolarization, potassium leakage channels allow potassium influx passively and this returns the ...
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What is the role of increased cytosolic calcium concentration after firing, in neuronal cell bodies?

I've come across several studies in which scientists were investigating various questions related to neural activity by focusing on neuronal cell bodies using Calcium imaging. As this article suggests ...
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To what extent does loss of neurons in the substantia nigra affect movement?

There is a substance known as MPTP that is capable of crossing the blood-brain barrier. Once it does so, it is metabolized into a toxin called MPP+, which then selectively destroys dopaminergic ...
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Can brain activity be restored after being stopped, assuming no cellular damage?

I was reading about cryonic preservation recently. In a separate place on the Internet, I've read that once brain activity stops and brain death occurs, the person is dead with no hope of recovery. ...
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Reference Request: Human visual system takes in $10^7$ bits/sec at the periphery and compresses it down to 50 bits/sec deep inside

In Sparse Components of Images and Optimal Atomic Decompositions by Donoho, 1998, the author claims that The human visual system is thought to do a tremendous job in achieving sparse ...
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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 ...
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Why/how does exposure to noise cause cochlear hair-cell loss?

I am trying to understand why listening to loud music - e.g. concerts or earphones at high volume damages hearing. According to the National Institute on Deafness the cause is physical. Most ...
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What is the purpose of descending auditory signals from the brain?

What might the purpose be of the brain having descending auditory signals from the brain? My textbook is very vague about this and I am just curious.
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By what mechanism do our nerves lengthen as people get taller?

How do nerves get longer as kids grow taller? I searched for an answer but I can only find information on the formation of nerves in embryos.
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Do astrocytes connect and chemically communicate with other astrocytes?

I am building a novel model of neural tissue for the purposes of Machine Learning and am currently trying to unpick the functions of the astroglia. The literature suggests that astrocytes ensheath ...
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What makes synapses stay “fixed”?

What makes synapses not move or pre- and postsynaptic cells neither touch nor move away from each other? I mean the synaptic cleft is a gap between the pre- and postsynaptic cells that is about 20 nm ...
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can auditory/ocular reflexes exist?

In the same way the knee-jerk reflex is a thing (I think the nerve signal doesn't go through the brain?), can stimuli received by the eyes or ears trigger "instantaneous" (faster than the brain can ...
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Can we “learn” reflexes?

Can we force our bodies to react to situations faster than our brain can think about them? Some reflexes I can think of off the top of my head: knee jerk reflex retracting hand when touching a hot ...
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Are cold weather tolerance and spicy food tolerance related physiologically?

If a person grew up in a cold place they happily walk outside in winter in short sleeves and shorts in places with mild Winters while the locals are bundled up in thick jackets. Spicy food with ...
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Cerebral/Cerebellar Cortex versus Deep Nuclei

I have troubles using the terms Cortex & Deep Nuclei, and 'Nuclei' in general. From what I understand, a brain has '3 matter types in accordance to anatomical locations' Superficial Grey matter - ...
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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 ...
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What physiological pathways lie behind inhalants hallucinogenic effect?

I searched through the web and surprisingly I found pretty much nothing on the physiology of hallucinogenic effects of inhalants. Any idea how people get high with inhalants (household and industrial ...
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Cardiac vs. muscles contraction

For the heart muscles, it is the Ca extra cellulaire that is necessary for the contraction, but for the skeletal muscles, it is the Ca intra cellulaire? One of my test MC responses was " In cardiac ...
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Why didn't these scientists restore electrical activity in this pig's brain?

This experiment was published in Nature Magazine: Pig brains kept alive outside body for hours after death. The researchers used a system called BrainEx to revive certain metabolic and physiological ...
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Is there a link between brain's energy consumption and human experience?

I was read the article (in Scientific American Mind) about energy consumption of brain. There are: Say you are learning a new skill—how to juggle or speak Spanish. Neuroscientists have made the ...
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What is the correct value of Neuronal Resting Potential,is it -65mV or -70mV

Some Books are showing the resting potential of neurons as -65mV Eg : NEUROSCIENCE-EXPLORING THE BRAIN,Fourth Edition,2016,Wolters Kluwer while Majority of internet sites(including Wikipedia) are ...
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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 ...
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Can disorders involving involuntary muscle twitches and spasms have a hypertrophic and increased residual muscle tension effect?

Meaning disorders specifically like myokymia, myoclonus (positive and negative) and fasciculations. From the section of the literature I've seen, sometimes passing mentions are made when the disorder ...
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Assumptions for Nernst Equation

While I am familiar with some of the conditions for the Nernst Equation, for example: 1) "The membrane is only permeable to one ion even if there are several other ions in the system" there is an ...
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Is it correct that the nicotinic acetylcholine receptor has nothing to do with Dopamin?

As I know Dopamine is almost exclusively produced via metabotropic receptors, is it possible for a nicotinic ACH receptor to influence a dopamineric neuron? Can a nicotinic ACH receptor cause a ...
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How many neurons do we have in our forearm?

I am developing a neural interface, getting signals from the forearm and mapping them to hand gestures. The question we have at the moment is what is the upper bound of information bandwidth that we ...
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Can motor neurons in the brain stem start movements?

Supposedly (consciouss) movement is started in the cerebral cortex. But some time ago I've read a research which stated it might be possible some movements (not specified which ones, probably mean ...
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Why do wild animals not eat in captivity?

I have rescued possums before but this is the first full grown opossum I took in. She was skinny unlike the one I have now for 3 years and healthy. I would not normally take in a grown animal like ...
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Double vision from one eye? [closed]

I have recently experienced getting double vision out of one eye. When I cover my dominant right eye the double vision corrects and become a solid image? I am not asking if it is possible to get ...
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Is the strength of presynaptic stimulus on the postsynaptic neuron affected more by the dendrites, or the cell body?

Is the strength of presynaptic stimulus on the postsynaptic neuron affected more by the properties of the dendrites & axon terminals, or the cell body & axon? Two years ago I asked a question ...
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human sight at 1000x while looking into the mirror [closed]

I noticed that my eyeballs have the ability to see in what appears to be 1000x. Setting the conditions: Look into a mirror while in a well lit room. (for me the lighting in my living room as opposed ...
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Understanding the derivation of the Nernst equation

I am trying to understand how the Nernst equation can be derived and am mostly referring to the explanation given in the book Theoretical Neuroscience by Dayan and Abbott. Given we have a ...
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What's the difference between the neuroendocrine system vs endocrine system?

This is what I have understood so far: Neuroendocrine system involved neuroendocrine cells (also known as neurosecretory cells) that receive nerve impulses by a sensory neuron to release ...

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