Effect of visual stimulation on the evoked response recorded at the vertex.

Previous research on the visual evoked brain response (VEBR) recorded from the occipital scalp indicates that this response shows a high degree of stimulus control. An evoked brain response can also be elicited simultaneously from the vertex response is affected to the same degree by several different aspects of visual stimuli as is the corresponding occipital response. The VEBR was recorded from the vertex of 3 human subjects as a function of changes in stimulus size and intensity. The results showed that the amplitude of the first major positive component of the VEBR was not reliably related to the stimulus parameters. It was concluded that the VEBR recorded at the vertex probably has its source in a distinct cortical generator which is not specifically related to the parameters of visual stimulation.