Realistic Neuronal Models

HARRY R. ERWIN herwin at mason1.gmu.edu
Thu Jul 28 21:03:41 EST 1994

I just finished Bartlett Mel (1993) "Synaptic Integration in an Excitable 
Dendritic Tree" (J. Neurophys., Vol 70, Nr. 3, September 1993, 
1086-1101). It's on modelling pyramidal neurons in detail. (He used Hines 
and Moore's NEURON model.)

Wow! I wish I had that model to incorporate into my Katchalsky nets. 
Extremely interesting. EPSPs apparently dissipate rapidly within the 
dendritic tree and at different rates depending on type. Some questions for 
the net:
1. Mel indicates that triggering the active zone around at the axonal 
hillock results in an antidromic signal that apparently wipes clean the 
accumulating signal in the basal dendrites. Is this the case? He doesn't 
discuss the apical dendrites.
2. I'm trying to understand the interaction between Golgi Type I and Type 
II neurons at reciprocal synapses. Do these fire in the absence of firing 
at the axonal hillock? I assume they do when hit by the antidromic 
signal in any case. 
3. The soma serves for the most part as a sink for the signals from the 
basal dendrites, isolating them from each other. On the other hand, the 
apical system operates similarly in some ways to Freemans NCA (my 
"activation network"). It tends to kindle and then fire massively. Golgi 
Type II neurons are built like pyramidal cells without the axon and 
apical system. Does this mean the soma is also an isolating mechanism in 
Type II neurons?
4. Is there evidence that the amplitude signal in pyramidal neurons is 
contributed by the apical dendrites, while the carrier wave is contributed 
by the basal dendrites?
5. Based on anatomy, I would expect the inhibitory cells of the cortex to 
synapse on the basal dendrites and soma. Do the cortico-corticals attach 
there as well?

Harry Erwin
Internet: herwin at gmu.edu 
Just a dumb engineer working on Katchalsky nets....

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