| Abstract: | The neurophysiological mechanisms underlying behavioral motivation and associative learning are described in an invertebrate “model” system, the carnivorous marine mollusc Pleurobranchaea. Feeding motivation can be controlled via nutritional history and is represented centrally in the feeding motor network as a change in the balance of synaptic excitation and inhibition at the level of interneurons that initiate feeding behavior, i.e., feeding “command” interneurons. Associative learning, induced by avoidance conditioning of feeding behavior, manifests identically at the level of the command interneurons, but is distinguished from non-associative motivational changes by processes that occur in identified neurons and pathways presynaptic to the command interneurons. Motivation and learning are therefore linked mechanistically by convergent neurophysiological mechanisms at the level of central neurons that initiate behavior. |
