Talk:Synapse

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Synapse is a featured article, which means it has been identified as one of the best articles produced by the Wikipedia community. If you see a way this page can be updated or improved without compromising previous work, feel free to contribute.

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That's as maybe, but I want also to add that there are different kinds of synapse. Most are chemical in nature, such as are already described. However, there is evidence for some very fast acting synapses which are electrical. These are reported to have been discovered in fish. Assuming that this has not been discredited, it would be worth having a section on electrical synapses. David Martland 00:06, 16 Jan 2004 (UTC)

Electrical synapses between GABA-releasing interneurons. Nat Rev Neurosci. 2001 Jun; 2(6): 425-33. Galarreta M, Hestrin S. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11389476&dopt=Abstract)

• Although gap junctions were first demonstrated in the mammalian brain about 30 years ago, the distribution and role of electrical synapses have remained elusive. A series of recent reports has demonstrated that inhibitory interneurons in the cerebral cortex, thalamus, striatum and cerebellum are extensively interconnected by electrical synapses. Investigators have used paired recordings to reveal directly the presence of electrical synapses among identified cell types. These studies indicate that electrical coupling is a fundamental feature of local inhibitory circuits and suggest that electrical synapses define functionally diverse networks of GABA-releasing interneurons. Here, we discuss these results, their possible functional significance and the insights into neuronal circuit organization that have emerged from them.

Yes, I think electrical synapses deserve a section, if not some systemic changes to admit to the recently broadened concept of synapse. Gap junctions didn't used to be considered synapses, but evidently now they are. 168... 16:31, 16 Jan 2004 (UTC)

Contents

1 Synapses and circuits 2 Synaptic Strength 3 Lack of references 4 Dimension of a synapse ?

Synapses and circuits

"Synapses define the circuits in which the neurons of the central nervous system interconnect."

was changed to "Synapses are circuits...."

Synapses are functional contacts for communication between nearby cells. Most synapses are between adjacent neurons, but some synapses are from neurons onto other cell types such as muscle cells. Synapses are of two types: electrical synapses and chemical synapses. Electrical synapses provide cytoplasmic connections between adjacent cells where ions can carry charges from one neuron to another. Chemical synapses provide cell-to-cell communication that is mediated by neurotransmitters. A neurotransmitter is a chemical that is released from one neuron, moves to a nearby neuron, and acts to modulate the physiology of the target cell. Neurotransmitters often work by binding to receptor proteins on the surface of cells. However, some neurotransmitters pass through cell membranes and directly influence target proteins inside their target neurons. Structurally, synapses are usually regions of close contact between adjacent neurons. Most neurotransmitters are packaged into vesicles at the presynaptic side of synapses. Most neurotransmitter receptors are concentrated in post-synaptic densities on the post-synaptic side of synapses. When activated by neurotransmitters, neurotransmitter receptors typically change ion flow across the surface membrane of postsynaptic neurons. Neurotransmitter receptors can have other effects such as regulation of gene transcription and the regulation of synaptic plasticity (changes in the functional and structural properties of the synapses themselves). The interconnected networks of neuronal cell bodies, axons, synapses and dendrites can be thought of as circuits that carry signals using a mixture of chemical synapses, electrical synapses, action potential propagation, and signals in the form of graded potential changes at cell surface membranes. JWSchmidt 23:41, 29 Mar 2004 (UTC)

This may be syntax curmudgeonery, but I think the original was more acurate. As you said, "The interconnected networks of neuronal cell bodies, axons, synapses and dendrites can be thought of as circuits" but that doesn't make synapses circuits themselves, as the sentence implies, only components of them. This stuck out to me immediately upon reading the article. I'm changing it to "synapses form the circuits" because that seems to say everything that's needed. 24.0.213.140 20:28, 29 Aug 2004 (UTC)

Synaptic Strength

• "Synaptic strength is the amount of current, or more strictly the change in transmembrane potential of the synapse."
• "One regulatory trigger of synaptic strength involves the simple coincidence sensory stimuli and action potentials in the synaptically linked cells."

1) I'm not sure why these two "sentences" seem to have a charmed life on the synapse page. They both should be fixed.

2) If you look in a neuroscience textbook (example (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?call=bv.View..ShowTOC&rid=neurosci.TOC&depth=2)) you will find discussion of synaptic strength mostly in the context of synaptic plasticity. I tried adding some basic information about synaptic plasticity. It was removed, leaving these two (above) problem sentences.

In summary, the "Synaptic Strength" section needs help but I'm not sure I should make any more effort to help it. JWSchmidt 00:47, 30 Mar 2004 (UTC)

Lack of references

Hi this article no longer meets the criteria for a featured article because it does not cite its sources. Please help fix this so that all featured articles can meet the same standards. Best would be the most trusted resources in the field being added, some print resources especially, but also online references are better than none. Those sources would likely help with good material to further improve the article anyway. - Taxman 23:00, Oct 26, 2004 (UTC)

I added two of the most common neuroscience textbooks (Kandel and Bear) as references. If anyone who contributed to this article had more specific references in mind, please add them. Sayeth 17:43, Nov 1, 2004 (UTC)

Would you say you are very confident that the material in those books agrees with what is here? Otherwise that is potentially dishonest to list them as references. - Taxman 19:11, Nov 1, 2004 (UTC)

Yes, both books state what is now the established dogma of synaptic transmission and action potential propagation, which is repeated in the wikipedia articles. In all likelihood, at least some of the authors of these articles used the Kandel or Brown textbooks as their source, since these are the primary textbooks for graduate and undergraduate courses in neuroscience. If the articles delved into more the esoteric mechanics of these neural functions, then there might be some conflict with the books, but as it stands now, they agree. Sayeth 17:03, Nov 2, 2004 (UTC)

Ok, sounds good to me. Thanks for helping and being willing to explain. - Taxman 18:35, Nov 2, 2004 (UTC)

I used Kandel & Schwartz in graduate school and think it's a perfect reference.

Dimension of a synapse ?

Which is the average size of a synapse ? It is probably smaller than a micron since the neurons size is between 5 and 150 microns, but I would like to know their real size.

It's hard to tell exactly what dimensions you're speaking of, but I'd bet you're asking about the distance between pre- and postsynaptic neurons. The gap is called the synaptic cleft and it is typically 20-30 nm across. Here's a nice visual (http://synapses.mcg.edu/anatomy/chemical/cleft.htm). --David Iberri | Talk 22:09, Apr 13, 2005 (UTC)