Cerebellum wide imaging of neural activity in freely behaving animals

PROJECT SUMMARY The stereotypic and relatively simple circuitry of the cerebellar cortex, with its highly conserved nature throughout evolution makes the cerebellum a very attractive circuit to understand fundamental neuronal mechanisms by which the brain performs input-output transformations that are needed not only for motor function but a spectrum of non-motor functions. A unifying view of the computations performed by the cerebellar cortex that incorporates its dominant parasagittal and transverse architectures has proved elusive. Recordings of cerebellar neuronal activity across multiple folia at relatively high spatial and temporal resolution are limited. Further, given the cerebellum’s involvement in several motor and non-motor processes, it is crucial to make these recordings in freely behaving mice in which the wide repertoire of behaviors is not impeded. Here, we propose to engineer a miniaturized ultra-widefield micro-camera array microscope (MCAM) capable of imaging a large area (24mm2) of the cerebellar cortex with cellular resolution. This MCAM combines several innovations, including a transparent polymer window implant for cellular resolution imaging, an array of epi-fluorescence micro-camera optics, along with complementary genetic approaches for sparsely labeling Purkinje cell populations in the cerebellum. In AIM 1, we will design and build an MCAM to be compatible with a cerebellum polymer skull implant developed by our collaborative team. Experiments will be conducted in head fixed mice to refine and optimize the opto-mechanical components of the MCAM. In AIM 2, we will deploy MCAM in freely behaving mice in open field arenas and iteratively refine the design of structural and optical elements to ensure robust motion and light artifact free imaging in freely behaving animals. We will then validate the utility of the cerebellum MCAM to measure cerebellar wide Purkinje cell activities and encoding of error signaling in ladder rung walking.