The visually evoked response. Binocular facilitation and failure when binocular vision is disturbed
R. Srebro
The visually evoked response (VER) caused by the horizontal sinusoidal
movement of a display consisting of a checkerboard with 15-minute checks of
relatively low contrast oscillating at 6.3 Hz is itself sinusoidal with a
frequency of 12.6 Hz. When viewed binocularly, the VER is 25% to 30%
greater in amplitude than the sum of the amplitudes for monocular viewing.
This binocular faciltation may be a VER correlate of normal binocular
single vision. It is lost in small-angle esotropes and in normals whose
binocular function is disturbed by a vertical prism placed over one eye.
Characteristic curves relating VER amplitude and phase angle to frequency
to oscillation of the checker-board display suggest that two "systems"
carry information to the visual cortex: a long and a short latency system.
In amblyopia, the long latency system may be selectively impaired.
