DEVELOPMENT OF TEMPORAL PROPERTIES OF PATTERN ELECTRORETINOGRAM AND VISUAL EVOKED-POTENTIALS IN INFANTS

The postnatal development of the temporal properties of the responses to pattern contrast reversal has been studied by recording simultaneously the pattern electroretinogram (PERG) and visual evoked potentials (PVEP) in infants 3-22 weeks old. The stimulus grating (0.5 c/deg) was either reversed in contrast sinusoidally at frequencies 4-10.5 Hz to study the temporal frequency function of steady-state responses, or square-wave reversed at 1 Hz to evaluate the peak latency of transient responses. Developmental changes of the shape and bandwidth of the temporal frequency function of both PERG and PVEP occur post-natally and are particularly pronounced between 13 and 20 weeks from birth, possibly indicating deferred maturation of classes of retinal and central neurons with higher temporal resolution. The peak latency of the PERG decreases during the age period tested to approach adult values towards the end of the fifth month. The rate of decrease of the peak latency of the PERG differs from. that of the PVEP, indicating that post-retinal factors contribute largely to the maturation of the latter, especially in the earliest life period.