Perceptual Science Series
Hemispheric Asymmetry: Implications for Vocal Learning and Auditory Memories
Dr. Mimi Phan
Monday, November 24, 2014, 12:00pm - 07:00pm
Rutgers University,. Department of Psychology
New neurons are added to specific regions of the vertebrate brain throughout life, and are thought to function in learning and the formation of new memories. Although many of these regions exhibit lateral differences in structure and function, differences in new neuron incorporation between the hemispheres have not been described. The talk today will address whether: 1) new neuron incorporation differs between the brain hemispheres, 2) the degree of hemispheric lateralization of new neurons is correlated with behavioral and physiological measures of learning and memory, and 3) lateralized incorporation of new neurons is maintained by behavior. The songbird provides an assay for assessing the contribution of new neurons to hemispheric specialization because songbird brain areas that serve vocal processing are functionally lateralized and receive a continuous influx of new neurons in adulthood. Songbirds are an excellent model system for studying the basic processes that serve vocal learning because they are among the few animals that learn their vocalizations through a process of vocal imitation similar to human speech learning. The data show that significantly more new neurons are labeled in a left auditory forebrain area than in the corresponding right region; moreover, the degree of asymmetry in new neuron numbers was correlated with the quality of song learning and strength of neuronal memory for recently heard songs. In birds with experimentally impaired song quality, the hemispheric difference in new neurons was diminished. These results suggest that new neurons may contribute to a division of function between the hemispheres that underlies the learning and processing of complex signals.