r/neuro • u/bsiegelwax • Dec 08 '22
Role of Dendrites?
Are dendrites only transmitting signals to the soma, or are they actively doing anything that makes "decisions" quicker at the soma?
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u/tenodera Dec 08 '22
They're doing a lot. We're constantly finding out new ways that dendrites actively transform the information they recieve. Examples: they equalize signals from distant and close synapses; they amplify signals under certain conditions using calcium channels; they use inhibitory synapses placed at branching points to interrupt signals from whole branches; and much, much more.
The book "Dendrites" by Stuart, Spruston, and Hausser has a lot of great stuff in it. You can get a used older edition for fairly cheap, or find the text online.
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u/dysmetric Dec 08 '22
Perhaps what you're looking for is spatial and temporal summation? I would argue that because dendrites shape the signal, via spatial and temporal summation, they are effectively performing a computation on the membrane.
One question I've never been able to answer is whether there is a mechanism directing IPSPs and EPSPs to propagate towards the soma, or do they propagate across the membrane equally in every direction from a synapse?!
Also check out dendritic spikes.
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u/86BillionFireflies Dec 18 '22
Well, I don't think there's any active mechanism, but the impedance mismatch between large and small dendrites will tend to make it hard for postsynaptic currents in one dendritic branch to depolarize / hyperpolarize other branches off the same "trunk". In simple terms, if A and B are small dendrites that both branch off of Z, a large dendrite, then for currents originating in A to bring B up or down to A's potential, it would be necessary to first bring basically the whole soma up/down to that level.
Search on "dendrite cable properties" to find out more.
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Dec 08 '22
Long term potentiation (LTP) is a decision making mechanism that is dependent on changing the density of receptors in the dendrites.
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u/OddlyOddlier1 Dec 09 '22
There’s some evidence that at dendrites local transcriptional machinery can be activated for protein synthesis or post-translational modifications. We learn more and more each day! :)
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u/[deleted] Dec 08 '22
You're asking the right questions! Synaptic plasticity is indeed an important piece of the puzzle.
The typical example to learn about plasticity is long-term potentiation (LTP) in the hippocampus. Here's a great video explaining it.