NEGLECT FOR LOW LUMINANCE CONTRAST STIMULI BUT NOT FOR HIGH COLOR CONTRAST STIMULI - A BEHAVIORAL AND ELECTROPHYSIOLOGICAL CASE-STUDY

WE describe a patient with a right hemisphere lesion involving the fro ntal lobe, the post-central gyrus and the superior parietal lobule. Be havioural testing demonstrated severe left unilateral neglect to low l uminance contrast stimuli, but not to high colour contrast stimuli. Ev oked potentials to Ion contrast luminance gratings presented in the le ft hemifield were not reliable. However, equiluminant coloured grating s presented in the same hemifield evoked reliable electrophysiological responses, although longer in latency than those evoked in the right hemifield. These findings su patient has severe damage of the high con trast sensitivity magnocellular pathway in the right hemisphere,with m inor involvement of the parvocellular pathway.