Modulation of Neuronal Output

Kevin Spencer kspencer at iti.org
Wed Jul 6 13:12:11 EST 1994


herwin at mason1.gmu.edu (HARRY R. ERWIN) writes:


>There is a slowly developing consensus that semantics in the brain is
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>carried in the synchronization of pulse trains, whose amplitude reflect
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>local levels of activation. This may be at the level of individual cells
^^^^^^^^^^^^^^^^^^^^^^^^^^^
>or neural masses. Walter Freeman has a partial model of how this can
>occur at the level of neural masses--sparse nerve cell assemblies (NCAs,
>my 'activation networks') when suitably activated enter a second mode
>dynamic (periodic in isolation, chaotic when interactive) that modulates
>the local level of activation. The difficulty with this model is that
>the modulation has to be multiplicative; if it is additive, the second
>mode dynamics swamp the local activation level or viceversa. Has anyone
>identified a mechanism for multiplicative interaction between neurons or
>neural masses? Is stochastic resonance a candidate?

>Please note that I may have garbled Freeman's model.

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

Don't you think it's rather premature at this stage of computational
neuroscience to presume that we know *anything* about something as high-
level as "semantics"?  Freeman and others are doing very important work
in understanding the dynamics of neural systems, but I find it hard to
believe that the dynamics of the olfactory bulb are likely to be similar
to the dynamics underlying human cognition.  We simply don't know enough
yet.

-----------------------------------------------------------
Kevin Spencer
Cognitive Psychophysiology Laboratory and Beckman Institute
University of Illinois at Urbana-Champaign
kspencer at p300.cpl.uiuc.edu / kspencer at psych.uiuc.edu
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