Monotic and dichotic fusion thresholds in patients with unilateral subcortical lesions

Tone gap detection thresholds under conditions of monotic and dichotic mode were measured from the three groups of subjects; patients with right subcortical lesions, patients with left subcortical lesions and normal individuals. A significant difference of the thresholds among the three groups was observed in the dichotic condition but not in the monotic condition. The patients with right subcortical lesions showed a gross deficit in temporal resolution even when the stimuli were presented dichotically. The results are discussed in relation to functional differentiation of right and left subcortical structures for temporal processing.