Neural Basis of Behavioral Flexibility

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Project Summary `Degeneracy' in network function has been observed in a number of species. In these situations one particular pattern of motor activity is encoded by more than one set of cellular and synaptic properties. A question of general interest is: how does this impact network function? Experiments proposed in this application will study degeneracy in a multi-tasking network in the context of `task' switching, i.e., the cessation of one type of motor program and the initiation of another. We will test a novel hypothesis that postulates that the ability to `task' switch is determined by the nature of the mechanisms that are used to pattern activity. In particular, we suggest that this is likely to be the case in a commonly observed situation, i.e., in the situation where modulatory neurotransmitters play an important role in configuring neural activity. Effects of modulatory transmitters generally persist, which creates a form of implicit memory. We suggest that this implicit memory can either impede or promote task switching. In more specific terms, our experiments are conducted in an experimentally advantageous network that mediates feeding related behaviors. Our experiments take advantage of considerable preliminary data that indicate that egestive patterns of motor activity can be induced in this network in at least two ways, i.e., they are encoded as two distinct sets of cellular and synaptic properties. Proposed experiments will determine whether this is the case, and will contrast transitions to ingestive activity from the two types of egestive configurations. We suggest that in one situation the network will be able to change the nature of the motor program relatively quickly, whereas in the other situation it will not. We will determine why this is the case in experiments that will analyze underlying mechanisms at both the circuit and cellular/molecular level. Switches in network activity are important for the survival of most species. In humans, costs associated with task switching can significantly impact performance. Nevertheless cellular and molecular mechanisms that facilitate or impede task switching have not been described. To our knowledge we are the only group working in a tractable model system that is studying this phenomenon at a cellular/molecular level.