Origin of the in vivo rat piriform cortex activity recorded with voltage-sensitive dyes: comparison of the optical signals and the field potentials.

The comparison of optical recordings and evoked field potentials recorded on the rat piriform cortex pointed out that both signals were strongly correlated. As the field potentials, the two waves of the optical signals originated from the mono- (direct olfactory bulb afferents) and polysynaptic (intrinsic association fibers) excitatory postsynaptic potentials. Such optical recordings will be used for studying spatiotemporal distribution of the piriform cortex activity.