DICHOTIC-LISTENING MEASURES OF BRAIN LATERALITY IN MANIA

Dichotic syllable and complex tone tests were used to compare performa nce asymmetries in manic patients (n = 35) with normal controls (n = 2 6) and to determine whether there were changes in laterality with remi ssion of the manic state. Relationships of performance asymmetries to treatment outcome and symptom features were also examined. Compared wi th normal controls, manic patients showed overall poorer accuracy, par ticularly for complex tones presented to the left ear, and they failed to show the normal left-ear (right-hemisphere) advantage for complex tones. Abnormal laterality for complex tones was present in patients w ho later responded to treatment but not in nonresponders. In the euthy mic state, patients showed improved left-ear accuracy for complex tone s and more normal perceptual asymmetry. These findings suggest that ma nia is associated with a decrement in right-hemisphere processing of c omplex tonal information.