DICHOTIC-LISTENING, EVENT-RELATED POTENTIALS, AND INTERHEMISPHERIC-TRANSFER IN THE ELDERLY

Objective: To determine the basis for the large, age-related asymmetries in dichotic listening performance scores reported by Jerger et al. (1994). Design: Behavioral and electrophysiologic responses to dichotic listening tasks in both verbal and nonverbal paradigms were obtained in four groups of subjects: young adults with normal hearing, elderly persons with presbyacusis, elderly persons with presbyacusis and marked dichotic deficits, and patients with lesions of the corpus callosum. Results: In comparison with the young group the two elderly groups showed an increasing left-ear deficit on the verbal task, and an increasing right-ear deficit on the nonverbal paradigm. The pattern of results obtained in the elderly persons with marked dichotic deficits was similar to the pattern of results in the group with callosal lesions. Conclusions: With age, there may be a significant loss of efficiency of interhemispheric transfer of auditory information through the corpus callosum. Such age-related deficit might have important implications for the effective use of binaural information by elderly persons.