The circuitry of the basal ganglia is complex and, despite many box and arrow diagrams in textbooks, poorly understood. We are using a combination of viral tracing, optogenetic, imaging, and electrophysiological approaches to understand how neurons in the basal ganglia are interconnected. Furthermore, using optogenetics, we are examining the properties of each synapse in order to assemble a detailed model of basal ganglia circuitry. Similar approaches are being used to understand the synaptic, cellular, and circuit consequences of dopamine and acetylcholine release. Lastly, in awake behaving mice, we are delivering perturbations of activity to specific elements of the basal ganglia to determine the functional impact that the activity of one class of neuron has on that of other neurons and nuclei.
Contributions to learned behavior
The proper function of the basal ganglia is necessary for the generation of purposeful, coordinated movements, as is made clear by diseases of the basal ganglia such as Parkinson’s and Huntington’s. In addition, the basal ganglia act in reward reinforcement to promote motor actions that lead to reward, a function that is hijacked by many drugs of abuse. We are examining the circuit elements that are modified within the basal ganglia by reward reinforcement learning. In addition, we are examining the necessity and sufficiency of activity of specific cell types within the basal ganglia in the reinforcement and execution of learned motor actions.
Although the basic patterning of the basal ganglia is laid out early in development, a great deal of synaptogenesis and circuit refinement occurs postnatally. We are examining the molecular signals and activity-dependent processes underlying postnatal development of the basal ganglia using a combination of genetic, anatomical, optogenetic, and electrophysiological approaches.