Abnormal orientation bias of LGN neurons in strabismic cats.

The reduced visual sensitivity of strabismic amblyopes is often accentuated when they view vertical as opposed to horizontal gratings ("vertical effect"). Earlier attempts to show neurophysiological correlates of the vertical effect in strabismic cats have yielded controversial findings. We now report the results of experiments in the lateral geniculate nucleus (LGN) that clearly demonstrate the reduced sensitivity of X-cells in strabismic cats to vertical gratings as compared to horizontal ones. We conclude that the neural basis for the vertical effect is present at least at the level of the LGN.