30.05.2016 15 s.t.
Response variations and stimulus discrimination: lessons from disinhibition
by Netta Haroush
from Technion, Israel Institute for Technology
MPI DS seminar room (0.77/0.79)
Inhibition is fundamental to sensory discrimination. At the level of the sensory envelope, where the anatomy of neural circuits is highly structured, inhibition sharpens the contrast amongst various stimulus properties. The impacts of inhibition on stimulus discrimination are not as clear when activity propagates to the less-structured higher relay stations. In this seminar I will describe a synthetic approach we took in an attempt to disengage the impacts of the structural component, using multi-site recordings from large random networks of cortical neurons. We investigate the effects of blocking the inhibitory synaptic transmission (disinhibition) on response variability, and on the separability of responses evoked from different spatial locations. We show that disinhibiton quenches variability of responses evoked by repeated stimuli through any given spatial source; this is true at the single unit and population levels. The organizing effect of disinhibition enhances the capacity of the network to classify input sources based on spike time relations. Firing rate based classification is, however, largely unaffected by disinhibition. Finaly, we show indications for coherent, wave-like propagation of activity under disinhibition. The preference of propagation through near neighbors is "compromised" under intact inhibition. This evidence is in support of inhibition demonstrating a non-literal lateral inhibition in random networks.
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