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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146 views

How optimal are the distances of voltage-gated ion channels on axons?

In both myelinated and not-myelinated axon segments ("axons" for short) there are theoretically maximal distances of voltage-gated ion channels beyond which propagation of the action potential would ...
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59 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 ...
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Can dopamine antagonists be used as dopamine upregulation?

Can dopamine antagonists such as Thorazine that are used to treat schizophrenia and bipolar be used to upregulate dopamine in the long term in healthy (non schizophrenic or bipolar) users to get a ...
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696 views

Why is the resonance frequency of a neuron defined by peak impedance?

I'm relatively new to the field of electrophysiology, so if anything is unclear or incorrect, please let me know. One thing that continues to confuse me throughout my reading is the property of ...
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46 views

How are targets formed for axon growth cones (CNS)?

Axons have growth cones which find a route to their target using multiple methods (guidepost cells, attraction to target, etc...). My question is, what is the process that actually forms the target? ...
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Question About the Physiology of Seizures

Absence seizures usually occur in children between ages 4 to 14 (Hopkins Hospital). Spontaneous remission occurs in 65–70% of patients during adolescence (Medicine Central). My question is what ...
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How is recruitment of multiunit smooth muscle cells fine tuned if they are innervated by varicosities?

In my physiology textbook (Silverthorn) and on wikipedia it says that: Multiunit smooth muscle tissues innervate individual cells; as such, they allow for fine control and gradual responses, much ...
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730 views

Acetylcholine and muscles- excitatory or inhibitory? (muscle atonia and myasthenia gravis)

I have heard that acetylcholine can be excitatory or inhibitory, but I am confused as to which it is when it comes to muscles. On the one hand, I believe that muscle atonia during REM sleep is ...
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38 views

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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29 views

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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27 views

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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164 views

Alpha-gamma co-activation

I am having trouble visualizing/grasping the necessity of alpha-gamma co-activation. My understanding is the following: When an external load causes stretching of the sensory muscle spindles, the 1a ...
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49 views

Are trees still carrying their leaves more likely to be felled by an autumn storm?

Is there evidence that trees still carrying their leaves are more likely to be felled by an autumn storm than trees already having lost their leaves? At first sight this seems plausible (and might be ...
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49 views

Chief Sensory Cells

What makes the second order neurons of posterior grey horn of spinal cord to be called as "chief" sensory cells? Why don't we call 1st order, or third order neurons or other second order neurones in ...
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41 views

Dorsal root fibres

How can dorsal root fibres be unmylinated though are responsible for conduction of pain and temperature? How is their conduction so fast without even being myelinated? Is presence of only one axon( ...
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54 views

Ion channels affected by gravity

In the literature I have found that action potentials behave differently when gravity is changed (cannot access fully). Action potential properties are gravity dependent. http://link.springer.com/...
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32 views

Pearson correlation of neural responses with it's linear estimation

I am trying to anderstand the following fact from this article (page 13): How can single neurons predict behavior Suppose I have a linear estimation of a stimulus: $ \hat{s} = \mathbf{w}^T(\mathbf{r} ...
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104 views

Are there calcium channel blocking neurotoxins?

I am learning about calcium ion channel blockers (CCBs) and am confused whether there are neurotoxins that are CCBs. If they exist, what is an example of a CCB neurotoxin? What animals use CCB ...
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43 views

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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32 views

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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30 views

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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47 views

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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71 views

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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43 views

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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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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48 views

How are neuromodulator receptors distributed?

Irrespective of where, when and how neuromodulators are released, eventually they are detected by some receptors in the membrane of a target neuron (typically G protein–coupled receptors) ...
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41 views

What is reaction time of a single c. elegans neuron?

What is the reaction time of a single c. elegans neuron? Is sensory neuron reaction to stimulus is similar to intermediate neuron passing a signal to motor neuron? What about chemical and electrical ...
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33 views

Distribution of dendritic spike generating ion channels on the dendritic tree

Is there evidence that dendritic spike generating ion channels are distributed unevenly on the dendritic tree, with higher density near the branching points of the tree than along the unbranched ...
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44 views

3D Object Modelling in the Brain

Could somebody point out the neuroscience literature dedicated to the modelling of 3D objects in the human mind? I'm interested in the brain regions, and particularly the details of the circuitry, ...
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56 views

Visual maps of the neuronal membrane

There are lots of visual maps of the brain as a whole, especially the cortex, that show the distribution of "features" over a two-dimensional map, e.g. the Brodman areas (their morphology and their ...
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46 views

Distribution of sodium–potassium pumps

How are sodium–potassium pumps distributed over the membrane of a neuron? Where are the most, where are the fewest? Or does this dependent on the type of neuron? Are there known and understandable ...
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74 views

Longest pathway from sensory to motor neurons

How long is the longest pathway a neural signal can take starting from a sensory neuron and ending at a motor neuron (without loops)? [This is a purely theoretical question concerning only the ...
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263 views

Why bipolar neurons in retina transfer information via graded potentials?

Why should bipolar cells prefer graded potentials to action potentials? My attempt: I know that graded potentials are better in processing information since stimulus is directly proportional to ...
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39 views

Why do nerve fibres rotate?

Background: Lemniscus (Latin lēmniscus, ribbon) is a strap of second order nerve fibres which twist as they ascend to the brainstem. Why do these these nerve fibres rotate? What could be the ...
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468 views

What is a unitary post synaptic potential?

I am reading the paper Cooperative subnetworks of molecularly similar interneurons in mouse neocortex and have encountered the term: "Unitary (excitatory or inhibitory) post synaptic potential". I ...
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26 views

Cytochrome Oxidase activity in neuronal cells

The abstract of this article says "...the entire neuron is often not metabolically homogeneous; most of the oxidative activity is usually found in dendrites." Why would the activity of cytochrome ...
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425 views

Is the central axon of pseudounipolar neurons in dorsal root ganglia typically myelinated

As I understand, sensory nerve cells in the dorsal root ganglion are pseudounipolar neurons, with a sole protrusion from the soma branching into a central axon (or functional axon) and peripheral axon ...
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131 views

Insulin and leptin action on Anorexigenic Neurons in Hypothalamus?

Receptors for Insulin are present on liver, adipose tissue and muscles. In addition, there are Insulin Receptors present in arcuate nucleus of hypothalamus, which influences anorexogenic neurons ...
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101 views

Where to go next with clustered C elegans neuronal time series

I'm doing some independent research with the C Elegans nervous system (with the OpenWorm project) and was looking for some guidance as to where I should go next. Right now, I'm dealing with calcium ...
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94 views

Why alcohol can't help with OCD?

I was thinking about influence of ethanol on our brain. We know, that ethanol can affect GABA receptors and increase flow of chlorine in our brain cells. So it makes signal weaker and slow our CNS ...
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98 views

Unmyelinated long axons in the sympathetic nervous system

I was recently looking over some textbook material (pdf) which claimed post-ganglionic fibers of the sympathetic nervous system are unmyelinated. This was surprising to me, since I had previously ...
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1answer
52 views

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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176 views

How do nerve impulses travel so quickly?

Nerve impulses must travel incredibly fast to achieve the functions they do. However, I have been taught that sodium ions move down the axons by diffusion (thus causing depolarisation of the next part ...
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177 views

How does the brain manifest and realize the intention to resist sleep?

The question title says it all. What happens in my brain when I resist sleep? I would appreciate explanations on neurotransmitter changes, what areas of the brain activate to resist sleep, what can an ...
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19 views

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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48 views

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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19 views

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.