[Effect of the color of visual stimuli on evoked human cortical potentials]

In subjects with normal colour vision and in those with its acquired defects, evoked potentials (EPs) were recorded in the primary and secondary areas of the visual cortex in response to monochromatic stimuli of equal energy and equal brightness. It is shown statistically that in case of stimuli of equal energy the EPs'characteristics were determined by the intensity and the colour of signals, whereas in case of equally bright stimuli the form, peak latencies and EP amplitude were actually dependent on the colour tone. These specificly colour changes in EPs were absent in colouranomals. The causes of a considerable individual variability of the connection between EP form and the colour are discussed. It is suggested that specific colour effects in the occipital EPs are caused by sensory opponent mechanisms of the visual system. It is shown that EPs may be used as an objective method for the estimation of colour discrimination in human subjects.