The EEG response to repetitive photic stimulation in various regions of the chicken brain

The EEG response in the chicken to repetitive photic stimulation was studied by frequency analysis and by the averaged response. Evoked responses were observable not only in stations along the visual pathway but also in broad areas apart from the visual pathway. The electrical activity in the archistriatum showed a marked response to flickering stimuli, indicating that this area is involved in the visual function in the chicken. In other telencephalic areas, photically evoked potentials could not be clearly demonstrated in the EEG records. In the hypothalamus and the nucleus rotundus of the diencephalon and in the nucleus reticularis superior of the mesencephalon, sinusoidal waves appeared during stimulation at 8-13/sec. No rhythmic after-discharge was observed following termination of photic stimulation. These finding are indicative of the difference of the visual response in the chicken from previously reported responses in other species.