Act natural: a review of new methods for assessing dopamine’s role in natural behavior

In patients with Parkinson’s disease (PD), loss of the key neurochemical dopamine (DA) in the basal ganglia leads to movements that are both more difficult to initiate and, once initiated, less vigorous. Yet, despite the robust link between basal ganglia DA loss and movement-related symptoms in PD, a mechanistic picture relating movement patterns with DA release has yet to emerge. We contend that one key hurdle in understanding this relationship is technical. Historically, the field has lacked the tools to easily resolve moment-to-moment changes in DA concentration across key brain structures while also capturing and quantifying fluid, naturalistic movements in freely behaving animals. In this review, we focus on recent technical advances that have fueled this type of experiment and how they have informed our understanding of DA’s role in natural behavior.