Visual Evoked Responses in Man: Normative Data.

The fundamental importance of the characteristics of the cerebral electrical response to a simple pulse of light in man is evidenced by the number of workers who have provided information about its features from conventional recordings. Detailed description awaited the development of more powerful analytical tools. With the recognition of the usefulness of photographic superimposition, correlational analysis, and summation techniques (Dawson, 1947; Brazier and Casby, 1951, 1952; Dawson, 1954; Barlow and Brazier, 1954; Brazier and Barlow, 1956), the way was opened for a new phase in the examination of the complexities of cerebral organization. The major features of the visual evoked response have now been outlined by CigLnek, Cobb, Dawson and others. Studies which have included an analysis of latency and polarity of individual components of the response are listed in TABLE 1. The present study was designed to furnish additional information about response morphology, particularly as it might vary in relation to recording site, with the hope that it might lead to an increase in the clinical application of the technique. Also, a preliminary survey of possible relationships between major features of the response and such normal variables as age, eye color, refractive error, color blindness, pupil size, subjective estimate of light intensity, prior night's sleep, alpha frequency, alpha amplitude, and alpha persistence was undertaken.