The ability to orient toward specific goals in the environment and control actions flexibly in pursuit of those goals is a hallmark of adaptive behavior. Instrumental conditioning is the simplest form of such behavior in which an animal or human learns to perform an action or sequence of actions in order to obtain reward or avoid punishment. Instrumental conditioning is composed of two distinct components: a goal-directed and a habit-learning component. In goal-directed learning, associations are formed between a given action and the goal-state (future reward or punishment). Instrumental behavior under goal-directed control can be altered rapidly following a change in the action-reward contingencies, or a decrease in the reward value of the goal itself. In habit learning, associations are made between the context (configuration of cues in the environment) and the given action, without encoding the goal itself. In contrast to goal-directed learning, habit learning is inflexible and leads to compulsive behavior. Once an action has become a habit (which happens over the course of learning), it is liable to be performed irrespective of the current value of the goal state.
The aim of this project is to determine the neural substrates of goal-directed learning and habit learning in the human brain, and characterize the process by which a goal-directed action becomes transferred to a habit. This will be accomplished by scanning human subjects using functional magnetic resonance imaging (fMRI) to measure neural responses during performance of simple instrumental conditioning tasks. We will use specific task manipulations, track changes in fMRI signals over the course of learning, and apply formal computational models to fMRI data in order to uncover these different components in instrumental conditioning. This R03 application is to support the initial development of a research program by the principal investigator who has just started in a faculty position as a prelude to a subsequent application under the R01 mechanism. Uncovering the neural mechanisms mediating goal-directed and habit learning could have important implications for understanding how some behaviors become """"""""habitized"""""""" - compulsive and difficult to change using """"""""willpower"""""""", as is the case in obsessive compulsive disorders, eating disorders, compulsive gambling and drug addiction. This research could ultimately be relevant in developing treatments for such conditions in which habitized or compulsive behaviors are returned to goal-directed control. ? ? ?
