Visual cortex responses to abrupt changes in the periodicity of rapidly intermittent light

Visually evoked potentials that are stimulated by period-jumps in a high-frequency modulated luminance have been detected and studied experimentally in monkeys. The visual responses are shown quantitatively by a Principal Components analysis to depend remarkably simply, in shape and in amplitude, on the period-jump stimulus. The response shape is nearly invariant, except that the early part of the response shows a distinctive (though slight) dependence on the sign of the period-jump. The response amplitude is approximately proportional to the magnitude of the period-jump of a given polarity. These features of the evoked potentials demonstrate an intimate association with a suprafusion transient phenomenon that has been observed psychophysically in man. The experimental behavior of the visual potentials also agrees well with theoretical predictions.