20 Hz rhythm of activity in visual system of perceiving cat.

Cats attended to either visual or acoustic moving stimuli in order to perceive the location of their disappearance, which signaled reward in left or right foodwell. The analysis of concomitant electroencephalograms revealed an elevation of the 20 Hz band in the Fourier spectra of activity of respective visual and auditory projection cortices. These oscillations appeared only on the trials that ended with a successful response. With use of directed transfer functions we were able to show that during the visual task, the 20 Hz frequency was propagated from the spot of appearance along the visual cortex, as well as towards the lateral geniculate nucleus.