Sensory perception (neurobiology query)

Ted edh at no.spam.thanks.oitunix.oit.umass.edu
Thu Aug 20 09:19:27 EST 1998


K C Cheng wrote:
> Re the 1st: action potentials are surely transmitted along dendrites as
> well. Lots of literature on this. Sorry, I'm too busy etc. right now to
> find and quote them for you.   But try the huge American Physiological
> Society Handbook, volumes on neurons.

I think you're confusing action potentials with postsynaptic
potentials.  Very briefly, action potentials are conducted along axons
after neural integration, which occurs at the base of the axon.  Action
potentials are "all-or-nothing" events; either they occur, or they
don't.  When they occur, they travel down the axon and induce the
release of neurotransmitters (or neuromodulators) at the axon's terminal
button, where the neuron synapses with another neuron.

Postsynaptic potentials (PSPs) occur in dendrites or the membrane of the
cell body as the result of receiving a chemical message from another
neuron.  They may be of varying strength, and are "summed up" in the
neural integration that occurs at the axon's base.  PSPs may either
excite or inhibit the generation of an action potential.

Alternatively, you may be thinking of the fact that an action potential
can travel in either direction down an axon.  However, almost all action
potentials start at the base of the axon, and thus travel from the base
towards the terminal button.

Anyway, you'll find a more detailed (and probably more satisfying)
explanation in just about any introductory book on neuroscience.

Ted
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