Numerous behavioral paradigms have been used to study the molecular and cellular basis of learning and memory; each has its particular strengths and weaknesses. One type of learning that has been overlooked until recently is the acquisition of gustatory memories. Animals readily learn new tastes and form gustatory memories which are largely processed and stored in the insular cortex. This model is an attractive one in which to study the molecular and cellular mechanisms of memory for several reasons detailed below. With a well-defined anatomy, and a foothold on intracellular signaling pathways, we propose to examine in detail how MAP kinase produces changes in neuronal physiology that contribute to the acquisition of gustatory memories. In particular, we will measure the phosphoryl-ation status of a number of potential MAP kinase substrates following exposure to a novel taste. A number of pharmacological inhibitors are now available to block the MAP kinase cascade, and these will allow a correlation of intracellular events with the behavior. Two substrates of interest include the NMDA receptor subunit NR2B, and the voltage-gated Kv4.2 potassium channel, where phosphorylation has been shown to change the kinetics of these channels. Using phospho-specific antibodies generated in the Sweatt lab, phosphorylation of Kv4.2 channels will be monitored following exposure to novel taste. Changes in gene expression will also be monitored, with a particular emphasis on Kv4.2 and NR2B. Finally, electrophysiological recordings in insular cortex will allow an examination of changes in neuronal physiology following activation of the MAP kinase cascade, further linking physiological changes with the behavior of acquiring gustatory memories.
