DESCRIPTION (provided by applicant): Successful development and adaptation requires, in part, proper performances in terms of how to respond, when to respond, and what consequences may follow responding. Defining characteristics of developmental disabilities and mental retardation are deficits in responding appropriately to environmental stimuli associated with various contingencies. Primary among these are the learning requirements to reach proper levels of responding. To understand the neural substrates underlying learning processes in healthy adults, previous PET and fMRI investigations image brain regions during delivery of reinforcers or punishers. The extent to which similar brain regions are involved in discriminating among stimuli associated with different contingencies is unclear, but equally important to understanding the neural processes involved in learning. This application presents data from a preliminary investigation using BOLD fMRI to examine relations between a history of discrimination learning and neural patterns of activation in a small number of adult human subjects. Preliminary results show stimuli associated with a reinforcement contingency produced a wide range of activation patterns when contrasted with a stimulus not associated with a contingency. Before conducting studies comparing subjects with and without differing levels of mental retardation, the investigators need to replicate their preliminary work with a sufficient number of non-mental retardation subjects to determine the usefulness of the stimulus-based imaging approach in either differing between conditioning histories or identifying neural substrates that map these histories.