Implantable 3D fluorescence imaging with high-speed, addressable laser scanning in moving mice

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Project Summary The goal of this work is to achieve high-speed optical fluorescence imaging of 3D brain volume in moving, behaving mice, using miniature scanning mirrors in an implantable, fiber-coupled microscope. Existing implantable microscopes for neural imaging primarily image a single focal plane or may alter image depth using scanning mechanisms that are slow and/or reduce the optical resolution. Scanning mirrors based on microelectromechanical system (MEMS) technology can be placed near the objective lens of fiber-coupled miniature microscopes, and achieve very high scanning frequencies. MEMS scanners based on active piezoelectric materials can rapidly steer laser light through all three axes in space. Fluorescence imaging can then be performed with deep imaging penetration using the multi-photon effect excited by an ultrafast laser. Our Specific Aims are to (1) demonstrate high-performance MEMS mirrors for axial and lateral scanning with speed and form factor appropriate for brain imaging; (2) integrate mirrors into a prototype implantable microscope, for 3D imaging at cellular-to-sub-cellular resolution; (3) collect images of neural activation from moving mice. Small mirror mass and active scanner control will prevent undesired motion artifacts and increase sampling frequencies in localized regions of interest within the image volume. The successful conclusion of this work would provide novel instruments for neuron behavior in the 3D brain environment over extended periods, necessary for the study of neural functions including locomotion, social behavior, and learning.