Short-Term Ssynaptic Plasticity Contributing to Learning: Roles of Neuronal Activity, Protein Kinases and Basal Synaptic Transmission

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Learning involves changes in the chemistry, function and structure of neurons in the brain. In order to study these changes, it is first necessary to identify the neurons that mediate the learned behavior and to determine the steps at which communication between these neurons is modified. The next stage in studying learning involves pinpointing exactly which molecules undergo alteration, and what part these molecules play in the overall functioning of the neurons. In this project a well-defined reflex behavior will be utilized in order to investigate how learning modifies neuronal signaling. Habituation and sensitization of defensive reflexes are two simple forms of learning that have been studied extensively in the marine mollusc Aplysia, and the insights gained have proven to be generally applicable to learning in higher animals as well. Habituation of the reflex results from repeated activation of the sensory neurons, and sensitization is largely caused by the action of the neurotransmitter serotonin. The principal investigator will examine which steps in the signaling process are altered by sensory neuron activity and by two endogenous enzymes that are activated by serotonin. Prior work in the his laboratory suggests that the two enzymes act at different steps in the signaling process, and that different sets of neurons may preferentially make use of one or the other of the enzymes. Experiments will be done by intracellular recording from individual sensory and motor neurons and application of reagents that affect the activity of these enzymes. This work will contribute to the basic understanding of how the brain learns, and as such may have implications for education. For example, the principal investigator has found that the two enzymes affect signaling differently depending on how much neuronal activity precedes the application of serotonin, suggesting that different learning strategies might be appropriate in different circumstances.