Questions tagged [synapses]

A connection between neurons, which is either continuous (in electrical synapses) or interrupted by a cleft (in chemical synapses), through which communication is established.

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The role of voltage-gated ion channels in chemical synapses

I am trying to understand the mechanisms underlying action potential generation on the cellular level. Typically, there is an emphasis on voltage-dependent permeability changes of Potassium (K+) and ...
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Exocytosis of synaptic vesicles

I'm reading the following paper: http://jcs.biologists.org/content/123/6/819 The part I am really confused about is when they say: Exocytosis appears to use two alternative pathways: clathrin-...
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excitatory-inhibitory synapse ratio

For each inhibitory synapse, how many excitatory synapses are in the brain? It is the same ratio along the animal kingdom or nervous system areas?
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Any volumetric data for areas of the brain?

I was trying to write an overview of AI and wanted to quantify some numerical data about the brain. It is easy to find many sources quoting 100 billion neurons. However, I would like to get the ...
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How fast does activity affect synaptogenesis?

How long does it take for the increased activity due to a novel stimulus to cause an increase in synapse generation? There are many studies which show that the number of synapses in the brain ...
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At what rate does synaptogenesis occur in adults?

From many articles, I can find the rate of synaptogenesis at its highest: roughly 580,000/minute (weeks 6-23 after conception). However, I'm having trouble finding the rate with which it occurs in ...
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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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Is summation linear in a passive membrane?

I am not too sure what it means for summation to be linear? I am running a simulation and as I decrease time for the second EPSP the amplitude decreases. Does summation being linear mean that there is ...
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What prevents neurones from touching at chemical synapses?

The synaptic clefts are really small, but the neurones which they are between do not touch even against forces like gravity. What really prevents them from coming into direct contact at the synapse, ...
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Calcium and nitric oxide: does a numerical relationship exist?

Currently, I am trying to understand how nitric oxide and calcium are related during the production of the former (I am not a biologist nor a chemist, so my knowledge about these topics is very poor). ...
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Plasticity between excitatory and inhibitory neurons?

All that I've learned about synaptic plasticity only concern the synapses between excitatory neurons. For example, all pyramidal neurons (excitatory) in the cortex have plastic synapses between them, ...
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Synaptic connectivity in the newborn's brain

In my understanding, learning is related to the strengthening and weakening of synaptic connections. Very roughly said: Synaptic connections that are used often are strengthened, those that are used ...
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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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The human brain in numbers II-A: synaptic connections per structural type [closed]

The overall number of synapses in the human brain is roughly 1,000 trillion, i.e. 10,000 synapses per neuron. I assume that each structural type of neuron (basket, pyramidal, ...) has a somehow ...
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Does a generator potential pass along a nerve the same way an action potential does?

I have read that a generator potential is a localized depolarization of a membrane. Does that mean that it does not pass along a neuron the same way an action potential does ? If not, then how do ...
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Understanding the picture of a synapse

I need help to see exactly what is going on here. According to the textbook here is shown a synapse, but I cannot quite see the things the textbook says are there. From what I understand: (1) At1 and ...
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Do presynaptic neurons and postsynaptic neurons have different compositions of neurotransmitter receptors and transporters?

For example if certain neurotransmitter is released, will there be neurons that won’t be even potentially affected, because it doesn’t have such type receptors?
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Why use embryonic neurons to study protein knockouts/mutants in long term potentiation?

Just wondering if anyone had some ideas about the question in the title. I'm just wondering why some papers use embryonic cultures of specific brain regions for neurones to test the effects of ...
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Why do SRIs help in serotonergic neurotransmission?

Serotonin reuptake inhibitors (SRIs) block the action of the serotonin transporter (SERT) which, according to Wikipedia, leads to an increase in serotonergic neurotransmission. Now this book ...
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Can neurotransmitter concentrations in the synaptic cleft add up if there are several impulses in quick succession?

When an electric signal reaches a chemical synapse, the signal is transmitted using neurotransmitters. Afterwards, the neurotransmitters are removed from the synaptic cleft. My question is whether it ...
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Human brain is superior than till-date computers, yet why we perform poor than computer?

Scientists found storage capacity of synapses by measuring their size. They found, on average, a synapse can hold about 4.7 bits of information. This means that the entire human brain has a capacity ...
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What does fail-safe mean in transmission at electrical synapses?

I'm reading a book named Neuroscience:Exploring the Brain recently. And in the chapter about synaptic transmission, it says "Transmission at electrical synapses is very fast and, if the synapse is ...
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Charge distribution to neuron connections

How is charge generated by the action potential is distributed to all of the neuron connections? From what I understand the total charge transmitted by a neuron once it fires is same for every neuron. ...
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How do neurons find each other?

Neurons form complicated networks in brains, but their connections can't be random (at least not entirely). Brains function similarly among all members of individual species, and that functionality is ...
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How is a synapse held in place?

Here is a question I've never asked myself until now: All textbooks show synapses with a decently large synaptic cleft between the axon terminal and the dendrite. How is this connection held in place ...
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How does the synaptic cleft exist?

I'm not asking why the synaptic cleft exists, i.e. what function it holds, rather how. So I know that the neurotransmitter diffuses across it, it is 20-40 nm wide and contains basal lamina (in NMJs at ...
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How long does a spiking signal last?

It is surprisingly hard to find information about the timing of neurons, in particular how long an action potential can contribute to the summation of a neuron. Is it on the order of milliseconds or ...
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What is synaptic clearance?

Please explain what the term synaptic clearance means. For example, what would dopamine synaptic clearance be? It is important to me in context of dopamine signaling variation due to difference in ...
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Synaptic pruning and selective elimination during adolescence

How does Synaptic pruning occur during pre-adolescence, adolescence and post-adolescence, after there is blooming overproduction of synaptic connections until the years of late childhood, and how does ...
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Synapse formation [closed]

I am trying to learn about neuronal synapse formation, but the literature is intimidating to someone with little background knowledge. I am interested in synapse formation in both human adults as ...
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Dendrodendritic synapse through axodendritic synapse at same dendrite?

Reading Wikipedia's article of dendrodendritic synapse, I find that: Dendrodendritic synapses are activated in a similar fashion to axodendritic synapses in respects to using a chemical synapse. ...
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Distribution of synaptic connections

What is the roughly the distribution of the various synaptic connections in the brain. Consider the following types: axoaxonic synapse between the axon of one neuron and the axon of another neuron. ...
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Differences between synaptic connections

Consider the following synaptic connections (from here): axodendritic - A term pertaining to an excitatory or inhibitory synaptic connection between the presynaptic axon of a transmitting neuron ...
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What is the latency between paired neuronal responses in the brain?

Is there any data on how long it takes for signals to propagate from one neuron to its neighbors in complex networks, such as the brain (particularly the neo-cortex)? If not, is there any reasonable ...
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Does tremor frequency generally increase as Parkinson's disease progresses?

I've been trying to research this question, but most if not all the on-line journals require costly subscription, and the studies that are posted look at tremor frequency with regards to other factors....
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Energy consumption of a resting synapse

What is the energy penalty of maintaining rarely used synapse? I'm wondering if forgetting is cheaper than remembering unnecessary details.
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What are the total number of action potentials in the human brain?

Is there an approximate figure of the total number of action potentials in the human brain? It's my understanding that there are ~ 60 billion neurons in the brain with ~ 100 trillion connections ...
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Chemical reactions at the synapse

For my course project, I am thinking of listing out major chemical reactions that occur at synapses, along with their temporal characteristics. I could not find any textbooks to use as a starting ...
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When the mind is highly active, roughly how many neurons become excited in one second?

I'm curios to know how many times neurons send signals in one second when the brain is highly active (Highly active meaning during difficult problem solving, or any task that might bring the brain to ...
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How does Sodium Valproate cause neural plasticity

I have been reading a fascinating paper: Valproate reopens critical-period learning of absolute pitch 18 individuals were given Sodium Valproate (VPA) for a fortnight during which they trained on a ...
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Can a postsynaptic neuron 'shut itself off?

I am an amateur interested in neuroscience and was curious whether there is a process by which a neuron or group of neurons would close their receptors and stop receiving signals from specific ...
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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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Can a neuron make a synapse onto itself?

I was wondering if a neuron can make a synapse to itself? I suspect that it would be extremely unusual for a neuron to do this. Anyway, has anyone seen even a single instance of this? Is the process ...
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Which pathways/mechanisms could control some Synaptic clefts in series by Somatic Nervous System?

I listened a talk where the speaker said that this can probably be possible by Weak Quantum Cognition Theory. I see that there is no evidence at the moment, only theory. I see no pathways by which ...
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Deducing synaptic strength from electron micrographs?

There are several promising techniques for connectomics based on iterative sectioning and imaging of tissue with scanning electron microscopes (e.g. FIB-SEM and ATUM) By looking at such micrographs, ...
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What is the full name of E. G. Gray?

E. G. Gray is Neuro scientist who found and described first the two major morphologically defined synapse types (Gray Type I (asymmetric) and II (symmetric)) in his work E G Gray (Oct. 1959). “Axo-...
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What happens in the synapse when cocaine administration occurs in the human brain

As far as i know when you accept cocaine in your blood some cocaine molecules reach some synapses in your brain and fill some Reuptake tunnels preventing the cell to simply "do not know that fired ...
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What's the difference between Cytoplasmic pool and Granular storage pool?

What's the difference between Cytoplasmic pool and Granular storage pool when speaking about neurotransmitters and synaptic cleft. I encountered this here: Amphetamine’s mechanism of action thus ...
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How are synaptic vesicles brought to the synapse?

I'm reading about how synaptobrevin is used to identify synaptic vesicles for tethering near the synaptic cleft. Since neurons have a synapse and dendrites, I'd like to know how exactly the vesicles ...
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Is it possible to lose synapses over time?

I mean, what if a person is for a long time submitted to conditions in which his mental capacities are not explored, are the synapses undone? I've heard that drugs may cause such an effect, but what ...