Two papers on Tuning Curves and Neural Control

[Gabriele Scheler]

The following two papers from CNS 2000 and CNS 2001 are available from my 
website 
http://wwwbrauer.in.tum.de/~scheler/pub/control.ps
http://wwwbrauer.in.tum.de/~scheler/pub/cns-paper.pdf


Signal Loss with Neural Controllers
Gabriele Scheler


We examine the effect of neuronal plasticity on information processing in a 
neural feedback-control system implemented by a recurrent structure.
We show that fine tuning of low-pass and high-pass filters on information
flow may lead to controlled signal degradation and signal loss, which is 
an important function for any self-recursive system.
We relate the filter function to neuromodulatory control, and discuss the 
biological realization of short-term and long-term plasticity effects. 


Dopamine modulation of prefrontal delay activity - reverbatory activity and 
sharpness of tuning curves

Gabriele Scheler and Jean-Marc Fellous

Recent electrophysiological experiments have shown that dopamine (D1) 
modulation of pyramidal cells in prefrontal cortex reduce spike frequency
adaptation and enhances NMDA transmission. Using four models, from 
multicompartmental to integrate and fire, we examine the effects of these
modulations on sustained (delay) activity in a reverberatory network. We find
that D1 modulation may enable robust network bistability yielding selective
reverberation among cells that code for a particular item or location. We
further show that the tuning curve of such cells is sharpened, and the 
signal-to-noise ratio is increased. We postulate that D1 modulation affects 
the tuning of "memory fields" and yield efficient distributed dynamic 
representations.


Gabriele Scheler
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Dr. Gabriele Scheler
ICSI
1947 Center Street
Berkeley, Ca. 94704