9310582 Ashe When one learns to associate a tone with a reward, the cells in the cerebral cortex of the brain that normally respond on hearing that tone become more discriminating. That is, the cells become more likely to respond to the rewarded tone, and less likely to respond to other tones that are not associated with reward. The sharpness of tuning of their receptive field improves. This type of receptive field tuning may be the cellular basis for many types of human learning that are dependent on the cerebral cortex. In this renewal of an NSF grant, Dr. Ashe will continue his investigations of the cellular mechanisms responsible for this receptive field sharpening. A particular strength of his approach is that he will use similar approaches both in vitro and in vivo. He will use newly developed pharmacological agents and physiological techniques to identify the complementary roles of three neurotransmitters in facilitating adaptive neuronal plasticity. The results should provide basic data on how learning occurs, and also help in the development of pharmacological treatments for memory loss due to aging, degenerative disease or head trauma. ***
