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Deep tissue optical focusing and optogenetic modulation with time-reversed ultrasonically encoded light
Haowen Ruan1, Joshua Brake1, J Elliott Robinson2
1Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
Science Advances
|December 12, 2017
Summary
Researchers achieved noninvasive light focusing deep inside living brain tissue using time-reversed ultrasonically encoded (TRUE) focusing. This technique precisely controlled neural activity and improved spatial resolution for optogenetics.
Area of Science:
- Biomedical optics
- Neuroscience
- Optical engineering
Background:
- Optical scattering in biological tissue limits light penetration depth.
- Conventional focusing methods are ineffective beyond several hundred micrometers in living tissues.
- Wavefront shaping techniques like TRUE focusing offer potential for deep-tissue light delivery.
Purpose of the Study:
- To demonstrate TRUE focusing in living brain tissue.
- To apply TRUE focusing for optogenetic modulation of neural activity.
- To evaluate the efficacy and resolution of TRUE focusing compared to conventional methods.
Main Methods:
- Utilized time-reversed ultrasonically encoded (TRUE) focusing.
- Applied the technique to 2-mm-thick living mouse brain tissue.
- Performed optogenetic stimulation in 800-μm-thick acute mouse brain slices at 532 nm.
Main Results:
- Successfully achieved noninvasive light focusing deep within living brain tissue.
- Demonstrated precise control over neuron firing using TRUE focusing.
- Achieved a fourfold increase in the spatial resolution of neuronal excitation compared to conventional lens focusing.
Conclusions:
- TRUE focusing is feasible in living brain tissue.
- TRUE focusing enables precise optogenetic control and enhanced spatial resolution.
- This advancement is a significant step towards practical biomedical applications of TRUE focusing.
