Neuroscience Seminar Series: Dr. Mark Howe, PhD
The direct and indirect pathways of the striatum have traditionally been associated with opposing influences on behavior, yet in vivo recordings generally revealed broad co-activation and similar behavioral correlates during movement and action. How these observations can be reconciled, and how relationships between the two pathways evolve during the learning and execution of sensory guided behaviors, remain unresolved. I will discuss recent work from our laboratory examining the organization of direct- and indirect-pathway activity across spatial and cellular scales during learned behavior. Using two-photon calcium imaging, we find that learning produces structured, dynamic imbalances between direct- and indirect-pathway populations within neuronal ensembles representing progress through goal-directed trajectories. These pathway relationships emerge with experience and cannot be explained simply by ongoing movement. To investigate how dynamics are organized across functionally distinct striatal circuits, we developed high-density optical fiber arrays which enable measurements of cell-type-specific activity and excitatory input at over 100 sites simultaneously throughout the striatum. These measurements reveal that low-level sensory and action-related representations are similarly expressed in both output pathways and closely reflect their inputs, whereas learned motivational representations become selectively differentiated between pathways within specific striatal regions. Together, these findings suggest a model in which learning transforms broadly shared input representations into spatially and temporally structured biases in striatal output. I will discuss how these dynamics may emerge through local circuit and neuromodulatory mechanisms, and how they could contribute to the selection, organization, and refinement of goal-directed behavior.
Angela Mohr
Email