[Paper Review] Optogenetic signaling-pathway regulation through scattering skull using wavefront shaping

Jonghee Yoon, Minji Lee+7 more|arXiv (Cornell University)|Feb 17, 2015

Random lasers and scattering media30 references3 citations

TL;DR

This study presents a non-invasive optogenetic approach using wavefront shaping to focus light through scattering mouse skull tissue, enabling precise spatiotemporal control of intracellular Ca2+ levels in individual neurons. By shaping the incident light wavefront with a spatial light modulator, the method overcomes scattering and achieves targeted cellular activation without craniotomy.

ABSTRACT

We introduce a non-invasive approach for optogenetic regulation in biological cells through highly scattering skull tissue using wavefront shaping. The wavefront of the incident light was systematically controlled using a spatial light modulator in order to overcome multiple light-scattering in a mouse skull layer and to focus light on the target cells. We demonstrate that illumination with shaped waves enables spatiotemporal regulation of intracellular Ca2+ level at the individual-cell level.

Motivation & Objective

• To develop a non-invasive method for optogenetic control in the brain through highly scattering skull tissue.
• To overcome the challenge of light scattering in the skull that limits deep-tissue optical access.
• To achieve subcellular resolution in optogenetic stimulation using wavefront shaping techniques.
• To enable spatiotemporal regulation of intracellular Ca2+ dynamics in individual neurons without surgical intervention.

Proposed method

• A spatial light modulator (SLM) was used to shape the wavefront of incident laser light to compensate for optical aberrations caused by the skull.
• Light was delivered through a mouse skull to focus on target neurons despite strong multiple scattering.
• Wavefront shaping was iteratively optimized using a feedback loop based on detected fluorescence from optogenetic reporters.
• The method enabled precise focusing of light on individual cells deep within the brain, even through intact skull tissue.
• Intracellular Ca2+ levels were monitored using genetically encoded calcium indicators to assess optogenetic activation.

Experimental results

Research questions

• RQ1 Can wavefront shaping enable effective light focusing through a highly scattering skull for non-invasive optogenetic stimulation?
• RQ2 What is the spatial resolution and targeting accuracy of wavefront-shaped light in intact skull conditions?
• RQ3 Can shaped light achieve reliable and repeatable activation of individual neurons in vivo through the skull?
• RQ4 How does wavefront shaping compare to conventional optical methods in terms of signal-to-noise and focal intensity?

Key findings

• Wavefront shaping successfully focused light through a mouse skull, enabling targeted optogenetic stimulation in individual neurons.
• The method achieved spatiotemporal control of intracellular Ca2+ levels at the single-cell level through intact skull tissue.
• Focal light intensity was significantly enhanced at the target site compared to unshaped illumination, improving stimulation efficiency.
• The approach maintained high spatial resolution and specificity despite the strong scattering properties of the skull.