PROPAGATING WAVES AND THEIR COLLISIONS IN VISUAL CORTEX
Propagating waves have been found in cerebral cortex during anesthesia,
sleep or in awake animals. We show here that such waves are found in
the primary visual cortex of awake monkey, and could be demonstrated
from voltage-sensitive dye (VSD) imaging. Further experiments showed
that the collision of two propagating waves produces a combined wave
which is less than the sum of the individual waves, so the propagating
wave exerts a suppressive effect. We use mean-field models based on
conductance-based spiking networks to show possible mechanisms for this
suppression. We found that the suppressive effect of propagating waves
can be explained by two mechanisms, the fact that inhibitory neurons
have a higher gain than excitatory neurons, and the fact that these
two contributions combine non-linearly with conductances. We speculate
on possible roles of such suppressive propagating waves.
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