Modulation of Neuronal Output

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

herwin at (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 
>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

Kevin Spencer
Cognitive Psychophysiology Laboratory and Beckman Institute
University of Illinois at Urbana-Champaign
kspencer at / kspencer at

More information about the Neur-sci mailing list