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Mandelbaum, Gil

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Mandelbaum

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Mandelbaum, Gil

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2017 - 20182

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Author's Publications: search.filters.isAuthorOfPublication.b5297286-cec0-4e13-b95a-9ce419b26c69

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    Dynamic illumination of spatially restricted or large brain volumes via a single tapered optical fiber
    (2017) Pisanello, Ferruccio; Mandelbaum, Gil; Pisanello, Marco; Oldenburg, Ian A.; Sileo, Leonardo; Markowitz, Jeffrey; Peterson, Ralph; Della Patria, Andrea; Haynes, Trevor; Emara, Mohamed S.; Spagnolo, Barbara; Datta, Sandeep; De Vittorio, Massimo; Sabatini, Bernardo
    Optogenetics promises spatiotemporal precise control of neural processes using light. However, the spatial extent of illumination within the brain is difficult to control and cannot be adjusted using standard fiber optics. We demonstrate that optical fibers with tapered tips can be used to illuminate either spatially restricted or large brain volumes. Remotely adjusting the light input angle to the fiber varies the light-emitting portion of the taper over several millimeters without movement of the implant. We use this mode to activate dorsal versus ventral striatum of individual mice and reveal different effects of each manipulation on motor behavior. Conversely, injecting light over the full numerical aperture of the fiber results in light emission from the entire taper surface, achieving broader and more efficient optogenetic activation of neurons when compared to the standard flat-faced fiber stimulation. Thus, tapered fibers permit focal or broad illumination that can be precisely and dynamically matched to experimental needs.
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    Tailoring light delivery for optogenetics by modal demultiplexing in tapered optical fibers
    (Nature Publishing Group UK, 2018) Pisanello, Marco; Pisano, Filippo; Sileo, Leonardo; Maglie, Emanuela; Bellistri, Elisa; Spagnolo, Barbara; Mandelbaum, Gil; Sabatini, Bernardo; De Vittorio, Massimo; Pisanello, Ferruccio
    Optogenetic control of neural activity in deep brain regions ideally requires precise and flexible light delivery with non-invasive devices. To this end, Tapered Optical Fibers (TFs) represent a versatile tool that can deliver light over either large brain volumes or spatially confined sub-regions, while being sensibly smaller than flat-cleaved optical fibers. In this work, we report on the possibility of further extending light emission length along the taper in the range 0.4 mm-3.0 mm by increasing the numerical aperture of the TFs to NA = 0.66. We investigated the dependence between the input angle of light (θin) and the output position along the taper, finding that for θin > 10° this relationship is linear. This mode-division demultiplexing property of the taper was confirmed with a ray tracing model and characterized for 473 nm and 561 nm light in quasi-transparent solution and in brain slices, with the two wavelengths used to illuminate simultaneously two different regions of the brain using only one waveguide. The results presented in this manuscript can guide neuroscientists to design their optogenetic experiments on the base of this mode-division demultiplexing approach, providing a tool that potentially allow for dynamic targeting of regions with diverse extension, from the mouse VTA up to the macaque visual cortex.