DISCONJUGATE ADAPTATION OF THE VERTICAL OCULOMOTOR SYSTEM

Conjugate post-saccadic eye drift can be induced in normal humans if a visual pattern is made to drift after every saccade, This study exami nes the ability of normal humans to create disconjugate vertical post- saccadic drift, Identical fuseable patterns were presented dichoptical ly, one to each eye, At the end of each vertical saccade one pattern d rifted up and the other down, by 5% of the saccade amplitude, Five sub jects were trained for 2-3 hr, Eye movements were recorded with eye co ils. Normal vertical saccades along the midline were remarkably conjug ate and post-saccadic drift was minimal. Training produced only small disconjugate post-saccadic drift (0.14 deg) but substantial saccade am plitude disconjugacy (0.70 deg), For several subjects, the induced dis conjugacies persisted even for saccades in the dark indicating that ad aptive changes occurred in the binocular coordination of vertical sacc ades. Apparently vertical disparate post-saccadic retinal slip is not sufficient to stimulate significantly the saccade pulse-step matching mechanism which is believed to control post-saccadic eye drift. The ch anges we observed aimed to reduce position disparity and not retinal s lip in each eye. Copyright (C) 1996 Elsevier Science Ltd.