Ultra-large field two-photon microscope to image transcortical brain dynamics

University Of California, San Diego, La Jolla CA

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Abstract

DESCRIPTION (provided by applicant): The PI introduces novel instrumentation to image and then analyze and quantify the whole- cortex electrical dynamics of neurons and the analogous vasomotor dynamics of brain vasculature. The spatial-scales encompassed by this instrument span from cell resolution - at the one-micrometer scale - to all of mouse cortex - at the then-millimeter scale. Large-scale brain activity encompasses the neurovascular issue of the redistribution of blood flow to areas of heightened metabolic need as well as patterns of blood flow secondary to vasomotor activity. It further concerns neurological issues of correlated neuronal activity in attention and decision making, distant signaling in multisensory processing and, at a more abstract level, issues such as the patterning of electrical waves in the brain. Further, large- scale Thus the proposed instrument gains broad intellectual merit as a means to diagnose neuronal and neurovascular processing that extends across different cortical areas. Our approach involves the design and realization of a novel, large-field in vivo two-photon microscope with an unprecedented ten-millimeter field of view with one micrometer resolution across the field. This is sufficient to image the entire cortical mantle in mouse with subcellular resolution. Our design and realization must meet the complex yet not insurmountable challenges of maintaining an aberration-free beam across large scan-angles, which are traditionally associated with chromatic and spatial aberrations. While there is limited guidance in the published literature on correcting such problems, we are able to successfully address these issues in a systematic way. Our novel microscopy will be combined with the use of transgenic animals in which individual specific cell types express a functional reporter. This will allow us t record from specific cell types - deep to the pial surface - and thus provide an anatomical basis for neuronal and neurovascular dynamics. Our approach provides a qualitative improvement of past, whole-field imaging techniques in which uniformly stained neuronal tissue was studied with neither depth nor cell-specific information. Beyond our scientific interests in neuronal processing and neurovascular coupling, our unique instrument will be of service to investigations of many other topics in the physiology of whole systems, including for example cell migration in development and regeneration as well as the flow of cells and tissue in tumor genesis and metastasis. Technical aspects of work will be broadly disseminated through the involvement of the PI and colleagues in graduate and post-graduate summer schools.