Localization and characteristics of the cortical waves associated with eye movement in the cat

Abstract

Movable and fixed bipolar electrodes were used to study the cortical PGO (ponto-geniculo-occipital) waves associated with eye movement during wakefulness and the REM (rapid eye movement) phase of sleep. During both states, PGO waves were localized primarily to the marginal and suprasylvian gyri. When electrodes were inserted in small increments into either gyrus, PGO waves were recorded as negative potentials which increased in amplitude as the deeper cortical laminae were approached, and then diminished slightly as the electrode passed into the underlying white matter. Studies correlating PGO waves with eye movement, measured cinematographically, demonstrated that every saccadic eye movement was associated with a PGO wave, the initial deflection of the wave lagging the onset of eye movement by 25–40 msec. However, no relationship was found between the amplitude, velocity, duration or direction of the eye movement and the amplitude of the related cortical wave. The data suggest that cortical PGO waves are the consequence of postsynaptic depolarization, in the region of the soma, of neurons located in the deeper cortical laminae. Both the cortical localization of PGO waves and their constant temporal relationship to eye movement are consistent with the hypothesis that this electrical activity is related to some aspect of oculomotor-visual integration.