Cortical coding.

Physiological photic and sound stimulation generated almost synchronous summated cortical evoked peak interval patterns over all regions of the head studied in man. Although the peak interval synchrony in all regions was obvious, it was observed that the peak amplitudes, and even phase relations varied over the different brain regions. The almost invariant peak time interval patterns for the input modalities studied, suggested a simple, generalized direct cortical coding that signaled immediate environmental change to the entire brain.