9520730 Information is encoded in the brain by modifications in cellular structure and changes in numbers of synaptic connections between neurons. The brain is organized into discrete neural circuits which process specific types of learned information and control specific behaviors. When the connections (synapses) within these neural circuits are altered, the output of the circuit changes and the behavior that it controls is modified. The objective of this research is to increase understanding of the development of a learned behavior and the neural circuitry which controls that behavior. The development of one naturally occurring learned behavior, bird song, will be related to the development of synapses within specific song-related brain areas. Song in birds is a complex learned behavior that is controlled by a highly localized system of interconnected neurons. Synapse numbers in song-related brain areas of normally raised individuals and of individuals that have had no opportunity for song learning will be quantified using high magnification electron microscopy. The singing behavior and social behavior of both groups will be analyzed to correlate neuroanatomical and behavioral changes. Preliminary data indicate that song-deprived individuals possess approximately 40% more synapses than normally raised individuals. This may indicate that song learning is accompanied by a large scale reduction in synapse numbers. This research will increase our understanding, not just of the neural basis for song learning, but of principles and mechanisms important for many different forms of learning in different species of animals.
