What do you think creates a habit? Habitual behaviors are defined by learning an automatic response to a certain stimulus. For example, you could have breakfast in the morning, even if you are not feeling particularly hungry at the time. Here, the action(having breakfast) is executed regardless of the goal(consume calories to feel full), but instead follows a learnt stimulus(time). Thus, habitual behaviors are not conducted for the aim of fulfilling a goal, but is dependent on the stimulus.
Calakos lab investigates the cellular and circuit changes in the brain(with a focus on striatum) as a behavior changes from goal-directed to habitual. This can be done by overtraining, where an initial goal directed response to press a lever to obtain food pellets becomes habitual/automatic over repeated trials. In this case, the point when the researcher knows the behavior is no longer goal-directed is when the mouse still presses the lever with same frequency, regardless of whether it was full or hungry before the behavioral test. This is called the devaluation test as you devalue the utility of the outcome.
Striatum is a brain area known to be involved in not only initiating or inhibiting movement, but also changing from goal-directed to habitual behavior. My research project is to image the afferent connections into the DMS and DLS-dorsomedial striatum and dorsolateral striatum- using retrograde tracer AAV. Active brain circuits during goal-directed and habitual behavior will be selectively labeled, which would be used to compare how the inputs into the DMS and DLS changes as lever press behavior turns from goal to habit.