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Basic Neuron Questions

Didier A. Depireux didier at tango.isr.umd.edu
Sat Apr 12 18:08:46 EST 2003

John H. <johnh at faraway.xxx> wrote:

> "Cortical neurons receive 3000-10,000 synaptic contacts, 85% of which are
> asymmetric and     hence presumably excitatory...Absent any inhibition, a

There's a lot more to the story than the number of synapses, there's also
the physical location of the synapse. Those from fibers arising from
thalamus and providing primary input tend to be close to the cell body, and
large. Therefore a single EPSP from a thalamic input is a lot more effective
than a large number of synapses being activated in the distal part of the
dendritic tree. There are also shunting synapses etc, so you need more than
just number of synapses before making these sweeping statements.


Didier A Depireux         ddepi001 at umaryland.edu  didier at isr.umd.edu
685 W.Baltimore Str      http://neurobiology.umaryland.edu/depireux.htm
Anatomy and Neurobiology                      Phone: 410-706-1272 (off)
University of Maryland                                      -1273 (lab)
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