EVENT-RELATED POTENTIALS RECORDED IN DORSAL SIMULTANAGNOSIA

Visual evoked potentials (VEPs) to central and lateral half field patt erned stimuli of 1, 2 and 4 cycles per degree (cpd) were recorded in a patient with Dorsal Simuitanagnosia due to bilateral lesions of parie to-occipital junction. VEPs consisted of the normal N1-P1-N2 component s with same spatial frequency sensitivity as in controls. VEPs had sim ilar latencies and amplitudes whether the patient could see or not the patterned stimuli. Event related potentials (ERPs) to visual and acou stic odd-ball paradigm were also recorded in the same patient. Visual ERPs consisted of an early NA-effect, and of N2-P3 components. P3 was recorded only from frontal, central and temporal derivations. The topo graphical P3 abnormality was, however, the same for visual and acousti c odd-ball paradigms. The amplitude of P3 was smaller when the patient missed visual stimuli. These findings show that severe bilateral lesi ons at the parieto-occipital junction, inducing Simultanagnosia, do no t obliterate VEPs or ERPs components.