Questions tagged [central-nervous-system]

The complex of nerve tissues including the brain and spinal cord, but excluding the peripheral nervous system.

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62
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4answers
8k views

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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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 ...
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How long can the brain survive during ongoing cardiac arrest?

There was this interesting discussion on CPR and defib in response to the question "Why can't we defibrillate the heart within 1 minute after ventricular fibrillation by electroshock?". Now I was ...
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2answers
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Is the bipolar neuron of the retina considered a sensory neuron?

Any neuron that participates in sending impulses from receptors to CNS are referred as sensory neurons. But I often see bipolar neurons of eye(which according to the above definition should be sensory ...
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1answer
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How are reflexes suppressed?

What neurophysiological process keeps reflex arcs in check? For example, the withdrawal reflex causes the hand to jerk back when the fingers touch something painfully hot incidentally. However, that ...
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1answer
317 views

Are all cone cells connected directly to the brain?

Coming from a computing science background, I noticed that cameras have orders of magnitude fewer wires than pixels. For example, the Raspberry Pi Camera v2 has 8 megapixels, but only 10 wires ...
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1answer
478 views

Can low temperatures induce a withdrawal reflex?

I read in "Essentials of Pathophysiology: Concepts of Altered Health States By Carol Porth" that "The thermal pain receptors are stimulated only by extremes of temperature such as "freezing cold" ...
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Why are some neurones unmyelinated?

As far as I am aware, most of the central nervous system consists of myelinated axons and most of the peripheral consists of unmyelinated. What is the reason for this? Would it not be more ...
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Do lobsters possess a nervous system to feel pain?

I was reading an article, which it mentions that lobsters do not have a nervous system: Lobsters have very poor eyesight and no nervous system. They walk slowly on the sea floor but are capable ...
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530 views

Why do nerve gas victims have chronic neurological issues?

The article on Wikipedia says the following: The effects of nerve agents are long lasting and increase with continued exposure. Survivors of nerve agent poisoning almost invariably suffer chronic ...
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3answers
570 views

Why are our muscles limited to 7 Hertz?

I have heard from a (usually very knowledgeable) friend before, that a human can only tap his fingers 7 times per second. I generalized this to "our muscles are limited to 7 hertz" When my wife ...
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How is information sent from the skin to the brain?

Say you have a needle, and you poke a very specific area on your left thumb. A signal gets sent from that nerve up your spine and into your brain. How does the brain know exactly where this signal ...
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Do skull bones have pain nerves (nociceptors)?

I recently attended an awake brain surgery for deep brain stimulation and it seemed to me that only the skin surrounding the drilled hole got local anaesthesia. I know that the brain itself does not ...
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1answer
402 views

Why is the hippocampus considered to be a cortical structure but not the amygdala?

I'm having some trouble understanding the anatomical differences that classify the hippocampus as a cortical structure but not the amygdala. I have included the screenshot of a diagram from Gray's ...
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2answers
797 views

Biological advantage of electric synapses

Electric synapses are synapses that do not process information but simply foward one action potential from one neuron to the next. There are no neurotransmitters, no inhibitory and exitatory ...
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1answer
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Is the autonomic nervous system only activated by internal stimuli?

My professor claims that the autonomic nervous system is only activated by stimuli from organs but I really feel like I've read that it can be activated by outside stimuli, although I'm not sure what ...
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Before I move my arm the brain sends signals - what causes the brain to send signals? [closed]

Please tell me what causes the brain to send signals, how does the brain send signals? can you tell me what happens between the point when you make an intention to pick up a glass of water, and before ...
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1answer
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How pain can stimulate the vagus nerve

I'm trying to find out why a prompt, severe, short pain is causing a stimulation of the vagus nerve. What could the physiological explanation be? Is that because the pain is triggering the ...
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1answer
132 views

Why are “itch signals” transmitted so slowly from the skin to the human brain?

In the second half of the BBC radio (and podcast) program Cats and Itch; Discovery, The Curious Cases of Rutherford and Fry Episode 2 of 5 the phenomenon and origin of the "itch" and related ...
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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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2answers
98 views

Neurons during Numb feeling

We become numb when there is short supply of blood to some parts, as mentioned here. If that is the reason, why don't neurons and other cells die at that part if they don't receive oxygen and other ...
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1answer
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What are these two nerves running parallel to the spine called?

I was looking for a human body nervous system, and often times i found a picture like the one below, where there are two nerves running parallel to the spinal column. I searched for it, but nothing ...
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1answer
139 views

Does GABA help or hinder anxiety?

This article https://www.prnewswire.com/news-releases/smartphone-addiction-creates-imbalance-in-brain-300558945.html Says both The researchers performed MRS exams on the addicted youth prior to ...
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1answer
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Photoreceptors and light with mixed frequencies

I am interested in how the activation of a, say, blue cone depends on the incident light. Wikipedia tells me this: , which describes how strong the activation of the blue cone is for light with a ...
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1answer
662 views

Why is Capsaicin injection not used instead of nerve surgeries for pain?

High concentration capsaicin kills c & a-delta nerve fibers permanently or at least long term. This has been known for 30 years. But capsaicin is only used in creams and patches, and not for ...
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1answer
370 views

Specific location where nerves converge

I'm looking for the "earliest" specific site where the 3 following nerves' sensory signals "converge": Trigeminal nerve Median nerve Superficial peroneal nerve By "earliest", I really mean the first ...
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1answer
702 views

Why does our mouth “water”?

Whenever we see something delicious, rapid salivation starts in our mouth. Also, it doesn't happen for all other food, which we eat regularly. So, Is there any particular use of "rapid salivation"? ...
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CNS lymphatic vessels around ventricles lat et 4th?

I am searching for precise locations of the lymphatic vessels of the CNS based on the applications of the article here. However, I did not find any when having a focus on the immediate region around ...
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Long-term effects of antihistamines on mind and CNS [closed]

Can maybe someone share knowledge or guesses on the following questions: Does the prolonged use of antihistamines cause long-term effects on mind or CNS? Are there any known evidences of their ...
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1answer
222 views

Alcohol consumption and central nervous system

After alcohol intake, the cerebrum related functions like vision and speech is affected first and later on there's problem with the cerebellar functions like balancing and hand-eye coordination. My ...
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2answers
98 views

At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'?

According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed. But according to this article, the heart ...
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1answer
39 views

How does (action potential) hyper-polarisation work?

I understand that after depolarisation, repolarisation and then hyperpolarisaiton occurs and that an area in hyperpolarisation is in its "refractory period". Why does this prevent Na+ ions diffusing "...
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1answer
672 views

How a nerve impulse reaches the correct destination?

Say your brain wants to retract your right hand. If there is some information coding playing a major role here, then what is the mechanism to find the correct path to reach the correct muscle? Or is ...
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1answer
131 views

In theory how fast could nerve signals travel if the nerve fibre was perfectly insulated?

My question is purely theoretical and my main aim is to find out the maximum speed that a nerve signal can travel within a nervous system and and whether this speed represents the physical limit of ...
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1answer
422 views

What specific sensory nerves act as receptors for “pins and needles” (neuropathy)?

According to this excellent answer, the difference between "pain" and "pins and needles" (neuropathy) is that different receptors (sensory nerves) trigger in reaction to different stimuli. Different ...
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1answer
158 views

Anatomy of nervous system's sensory pathways

When I touch my hand on a hot stove, I feel pain. I'm interested in knowing all the main "endpoints" (components/parts of the body) that are involved in relaying this pain signal. As I understand it ...
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1answer
143 views

How and where do nerves share pathways to the brain?

I am interested in understanding how pain receptors send signals to the somatosensory cortex (the part of the brain that registers various nerve signals such as pain, presure, temperatures, etc). ...
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1answer
95 views

Electric Shock To Human Body [closed]

What happens in our body when we get an electric shock?
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Is the CNS vascularized?

I was under the impression that the CNS is never penetrated by blood vessels, which explains why one never sees them in histological samples. However a google search reveals I am wrong. So can ...
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0answers
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Physiologically, how can stress/anxiety cause neuropathy?

According to the Mayo Clinic, stress/anxiety can cause "pins and needles" (neuropathy) sensations all over the body. But how can this be? My understanding of the sensory pathway is that sensory ...
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1answer
45 views

Does the nature of nervous impulses give us a finite number of things we can perceive?

This is a subject that is very disturbing to me and one that I've been obsessing over for years. I warn you now that this is probably not the sort of thing you get asked on this website and I'm not ...
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2answers
9k views

Why we shiver/tremble/shake while performing some work which requires high accuracy?

Shivering when nervous or anxious is a common thing. But, shivering or trembling sometimes also occurs when we are performing a work which requires high accuracy. In such case, our whole body doesn't ...
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1answer
48 views

Seizures and blood pressure

A seizure is basically a synchronized firing of neurons as opposed to the more common unsynchronized firing taking place during normal neural activities. However, I am uncertain if the exact technical ...
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1answer
38 views

Results of self-administration study about pain in honeybees?

There research on nih.gov about ability of bees feel pain. But I can't understand their conclusion. Could you provide necessary excerpts here from those study so it would be clear what conclusion they'...
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1answer
2k views

Differences in the action of Scopolamine and Atropine

Both Scopolamine and Atropine are muscarinic antagonists, having essentially the same action: blocking parasympathetic nerve receptors. The action on the brain by muscarinic antagonists is presumed ...
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2answers
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What is the difference between the neural tube and the dorsal ventral cord?

I was wondering what the difference is between the neural tube and the dorsal ventral cord. I know that the neural tube forms during embryonic development from the ectoderm layer that folds inwards. ...
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1answer
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Can signals travel “backwards” in the sensory pathway?

My understanding of the "sensory pathway" is that its a linear, directional pipeline as follows: Nerves (fire various signals depending on the type of sensors they are) Fibers (transmit signals from ...
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1answer
81 views

Why are spinal nerves considered a part of PNS while the spinal cord is a part of CNS?

So from my common understanding, CNS consists of brain and spinal cord, and PNS consists of everything else. But the spinal nerves - the nerves connected to the spinal cord - why are those considered ...
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1answer
528 views

Examples of seeking behavior by brainless animals

Are there any examples of brainless animals (e.g. jellyfish) exhibiting seeking behavior, such as following smell or light gradients towards food, or following hormones towards mates?
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Can the spinal cord contain an “epileptic focus”?

I was wondering, is there a possibility of an something similar to an epileptic focus to exist within the spinal cord? Note I am using the terminology "epileptic" loosely here, principally for the ...