LATERALIZATION OF AFFECTIVE PROSODY IN BRAIN AND THE CALLOSAL INTEGRATION OF HEMISPHERIC LANGUAGE FUNCTIONS

Although affective prosody appears to be a dominant function of the ri ght hemisphere, its degre of lateralization has not yet been establish ed since various publications have reported affective-prosodic deficit s following left brain damage in association with aphasia. This paper explores the mechanisms underlying affective-prosodic deficits followi ng left and right brain damage by testing the ability of subjects to r epeat and comprehend affective prosody under progressively reduced ver bal-articulatory conditions. The results demonstrate that reducing ver bal-articulatory conditions robustly improves the performance of left but not right brain damaged patients, a finding that supports the supp osition that affective prosody is strongly lateralized to the right he misphere. However, the performance of left brain damaged patients was not correlated to the presence, severity, or type of aphasic deficit(s ). Based on functional-anatomic correlations for spontaneous affective prosody and affective-prosodic repetition, deep white matter lesions located below the supplementary motor area that disrupt interhemispher ic connections coursing through the mid-rostral corpus callosum may co ntribute to affective-prosodic deficits that are both additive and ind ependent of any aphasic deficits. Zn light of these and other findings , various anatomical, functional, and maturational hierarchic relation ships between the affective-prosodic and verbal-linguistic aspects of language are posited in order to help further explain discrepancies th at exist in the literature regarding the neurology of affective prosod y. (C) 1997 Academic Press, Inc.