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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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How does defining cell assembly by giving weightage to impact caused as opposed to strength of connections change our current paradigm?

Buzsaki, in his paper Neural Syntax: Cell Assemblies, Synapsembles, and Readers, seems to suggest that instead of using synaptic strength and connectivity as a defining feature, a (dynamically ...
3 votes
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Why electrical synapses are more common in invertebrates?

I suppose it's because they live in an environment where there's a constant vulnerability to predators and they need to respond quickly. But it's not really the case for many invertebrates and besides ...
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Is colocalisation of a protein with a presynaptic marker sufficient evidence to say that the protein is a component of axon terminals?

I am reading journal papers about the subcellular localisation of the insulin receptor (IR) in neurons. I have read a paper stating that IR is highly enriched at synapses, localising to both the ...
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1 answer
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Why chemical synapses are more common?

Reading into the types of synapses I found out that there are two types of them; electrical and chemical. chemical synapses use neurotransmitters to transmit impulses, are slower than electrical ...
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Im struggling to see how these are presynaptic terminals/knobs and not post synaptic

How are these presynaptic terminals ? The action potential is generated at the axon hillock and moves down the axon (in this case to the right) , then at the end of the axon should be axon terminals ...
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1 answer
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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 ...
17 votes
3 answers
568 views

Under what conditions do dendritic spines form?

I'm looking for resources or any information about the formation of dendritic spines and synaptogenesis, especially in relation to how new connections are formed on a daily basis. Does the ...
2 votes
1 answer
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Cumulative synaptic transmission delay

Assume the following: there are at least 10^11 neurons in the human brain there are approximately 10^14 synaptic connections in the human brain (because on average each neuron gets inputs from ...
2 votes
2 answers
341 views

What determines the influx of calcium ions in the voltage-gated ion channels?

Calcium channels play a crucial role in neuronal signaling by helping the synaptic vesicles to fuse through the synaptic active zone and release their neurotransmitters. My question is, at a given ...
3 votes
1 answer
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Are synaptic boutons always located on axons?

I am learning about the protein Synaptophysin and I have read that it is an integral membrane protein localised to synaptic vesicles. I have also read that it is a specific and sensitive marker for ...
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1 answer
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What is meant by the term synaptic targeting?

I am studying whether a protein interacts with the mitochondria in the synapses of neurons and I have come across the term "synaptic targeting". I am reading this paper and I have come ...
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1 answer
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Definition of synaptic strength

The canonical definition of action potentials found in textbooks states that action potentials are all alike in shape. From techniques such as spike sorting which are used to attribute ...
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Synapses of inhibitory neurons

I sometimes read of "inhibitory synapses". But I understand that when the neuron is inhibitory, all of its synapses will be inhibitory (so it is a property of the neuron, not only the synapse) - is ...
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Electrical transmission vs Chemical transmission

"The advantage of electrical transmission, apart from speed, is it can favour synchrony in firing. For example, in the brain stem a nucleus called the inferior olive can generate oscillations due to ...
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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 ...
1 vote
2 answers
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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 ...
2 votes
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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 ...
3 votes
1 answer
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What makes synaptic vesicle release probabilistic?

The fusion of synaptic vesicles (SVs) with the plasma membrane of the active zone (AZ) upon arrival of an action potential (AP) at the presynaptic compartment is a tightly regulated probabilistic ...
6 votes
1 answer
849 views

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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What are the chemicals in the gap at a synapse? [duplicate]

I am learning about (introductory level) biological psychology and the synapse structure came into mind. I do understand that neurotransmitters are transmitted between two neurons via the synapse ...
4 votes
1 answer
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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 ...
3 votes
2 answers
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What material fills the synaptic cleft? Is it water?

The synaptic cleft is the gap between the pre-synaptic and post-synaptic neurons, and neurotransmitters are transferred between the neurons within this region. What substance exits in this space, is ...
1 vote
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How long does it take the neurotransmitters to diffuse accross the synaptic cleft?

Neurotransmitters get from the pre-synaptic neuron to the receptors on the post-synaptic neuron by diffusion across the gap between these two (the synaptic cleft). My question is, how much time does ...
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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 ...
2 votes
1 answer
873 views

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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1 answer
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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 ...
3 votes
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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 ...
4 votes
1 answer
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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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1 answer
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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 ...
2 votes
1 answer
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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, ...
3 votes
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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). ...
5 votes
2 answers
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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 ...
10 votes
2 answers
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How does an inhibitory synapse communicate to the cell body of a neuron?

I picture a neuron as having multiple trees of dendrites attached to the cell body with a single axon leaving the cell body. I believe the cell body near the axon root makes the decision to fire or ...
2 votes
1 answer
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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 ...
2 votes
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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 ...
3 votes
1 answer
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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 ...
5 votes
1 answer
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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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1 answer
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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 ...
14 votes
2 answers
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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 ...
5 votes
2 answers
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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 ...
2 votes
1 answer
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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 ...
2 votes
4 answers
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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 ...
5 votes
1 answer
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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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1 answer
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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. ...
7 votes
2 answers
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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 ...
6 votes
1 answer
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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 ...