Deep tissue optical focusing and optogenetic modulation with time-reversed ultrasonically encoded light

Haowen Ruan, Joshua Brake, J. Elliott Robinson, Yan Liu, Mooseok Jang, Cheng Xiao, Chunyi Zhou, Viviana Gradinaru, Changhuei Yang
2017 Science Advances  
Noninvasive light focusing deep inside living biological tissue has long been a goal in biomedical optics. However, the optical scattering of biological tissue prevents conventional optical systems from tightly focusing visible light beyond several hundred micrometers. The recently developed wavefront shaping technique time-reversed ultrasonically encoded (TRUE) focusing enables noninvasive light delivery to targeted locations beyond the optical diffusion limit. However, until now, TRUE
more » ... has only been demonstrated inside nonliving tissue samples. We present the first example of TRUE focusing in 2-mm-thick living brain tissue and demonstrate its application for optogenetic modulation of neural activity in 800-mm-thick acute mouse brain slices at a wavelength of 532 nm. We found that TRUE focusing enabled precise control of neuron firing and increased the spatial resolution of neuronal excitation fourfold when compared to conventional lens focusing. This work is an important step in the application of TRUE focusing for practical biomedical uses.
doi:10.1126/sciadv.aao5520 pmid:29226248 pmcid:PMC5722648 fatcat:h3h6lge5ffcv3fgnkio3tzhmvu