Application of pattern evoked potential techniques for evaluating infant perceptual systems.

An evoked potential (EP) test was developed to aid in the diagnostic evaluation of a 16-week-old infant of initially unknown pathology and degree of perceptual deficit. Patterned stimuli were presented at two repetition rates to challenge the infant's visual and auditory information processing capabilities. The data were compared to those obtained from a "normal" infant of the same age and sex and, where possible, to normative population data. The EP data indicated the following: (1) the "suspect" infant's occipital response to visual pattern was abnormal in terms of waveform characteristics and in the relationship of its amplitude to spatial frequency of pattern; (2) in comparing brain response to 1 Hz and 6 Hz stimulation rates, the "suspect" infant's occipital EPs were abnormally attenuated for the faster presentation rate when a patterned visual display was part of the stimulus complex; (3) an auditory speech sound produced equivalent EP effects in both infants. These data indicated that the "suspect" infant's perceptual deficit was restricted to the processing of visual pattern information, possibly due to abnormal functioning of the geniculo-striate system. Subsequent tests and the diagnosis of ocular albinism corroborated the results of the abnormalities suggested by the EP procedure.