Disorders of vocal emotional expression and comprehension: The aprosodias

Language is traditionally considered to be a dominant function of the left hemisphere because of its role in modulating the propositional or literal aspects of language (what is said). This chapter, however, will address the vital role of the right hemisphere in modulating the nonverbal, affective-prosodic aspects of speech (how it is said) that are essential for appropriate interpersonal interactions, communication competency, and psychosocial well-being. Focal right hemisphere lesions cause various disorders of affective prosody (aprosodic syndromes) that are analogous to the various aphasic syndromes that occur following focal left hemisphere lesions. Disorders of affective prosody may present clinically as loss of psychosocial well-being with disruption of interpersonal relationships. This chapter will review the research published over the last four decades that has helped to elucidate the neurobiology of affective prosody and the pathophysiology underlying the aprosodic syndromes.