Understanding and controlling the function of the brain is a challenge in modern neuroscience. Optogenetics as a new tool in neuroscience provides an effective way of manipulating a specific cell type by light stimulating microbial opsin expressed cells on a timescale of milliseconds. Typically, light delivery into targeting areas is achieved using optical fibers coupled to external laser diodes or light emitting diodes (LEDs). The optical fibers are inserted into the skull to stimulate the neurons, which is impractical for daily use. Also, scattering processes limit the depth to which externally focused light can penetrate tissue. In this paper we present that ultrasound can be used to define and steer the trajectory of light within scattering media by exploiting local pressure differences created by acoustic waves that result in refractive index contrasts. We demonstrate the application of this technology can be used for confining light through mouse brain tissue for optogenetics applications.

Keywords: Acoustic pressure, Brain tissue, Optogenetics, optical modulation, refractive index.

Full-Text [PDF 480 kb]   (367 Downloads)