Dynamically controlled light delivery over large brain volumes through tapered optical fibers

Abstract

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 large brain volumes or dynamically selectable subregions.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.

Mechanoluminescent Light Sources Based on Nanostructured Systems for Biomedical Applications: A Review

“…63 Since brain tissue strongly scatter and absorb visible light, the conventional optogenetics typically involves invasive implantation of an optical fiber for delivering light to selected brain regions. 64,65 However, such implantation may cause irreversible acute damage and chronic immune responses in the brain tissue. 66 Additionally, fixed optical fiber can only deliver light to specific brain regions, restricting their ability to modulate complex neural circuits distributed across multiple brain regions.…”

Deep brain cancer metastasis detection with wide-volume Raman spectroscopy through a single tapered fiber

“…To tackle this challenge, we view tapered optical fibers (TFs) as a promising implantable optical system. Owing to the mode-division de-multiplexing properties of a narrowing diameter section (10), TFs can exchange photons with the surrounding tissue over implant depths greater than 1 mm and have already been employed for large-volume optical neural interfaces to control and monitor neural activity in freely moving mice (11,12). The narrowing diameter of these implants (from 230 µm at its widest to 1 µm at the tip) reduces tissue reaction with respect to standard fiber optics (13) and establishes photonic properties that support a wide palette of optical detection strategies (14,15) from the visible to the near infrared range.…”

Visible Wavelength Beam Steering in Silicon Nitride Nanophotonic Phased Arrays with a Supercontinuum Laser

“…However, these components form illumination patterns in free space, and the penetration of visible to near-infrared light (400 -1100 nm) is limited by attenuation to only about 1 mm from the brain surface in rodents [7]. To bring light into deep brain regions, implantable optical devices are being investigated, including optical fibers [8][9][10], miniature gradient index (GRIN) lenses [11][12][13][14], and silicon (Si) neural probes with micro light-emitting diodes (µLEDs) [15][16][17][18], organic LEDs [19], or integrated nanophotonic waveguides [20][21][22][23][24][25].…”