Exploring two-photon optogenetics beyond 1100 nm for specific and effective all-optical physiology

Area of Science:

• Neuroscience
• Optical Imaging
• Optogenetics

Background:

• Two-photon (2-P) all-optical methods integrate in vivo calcium imaging and optogenetic modulation.
• Existing methods face challenges with photostimulation artifacts and precise action potential detection.

Purpose of the Study:

• To refine two-photon all-optical approaches for artifact-free in vivo experiments.
• To optimize laser parameters for enhanced specificity and efficacy in neural circuit interrogation.

Main Methods:

• Combined in vivo juxtacellular recordings with GCaMP6f-based 2-P calcium imaging in mouse visual cortex.
• Utilized extended-wavelength-spectrum laser sources (1100-1300 nm) for optogenetic stimulation to minimize artifacts.
• Developed and tuned a detection algorithm for 100% specific identification of action potential-related calcium transients.

Main Results:

• Achieved artifact-free all-optical experiments using optogenetic stimulation between 1100 nm and 1300 nm.
• Identified 1100 nm as the optimal wavelength for maximizing the efficacy of evoked calcium transients in GCaMP6f/C1V1-co-expressing neurons.
• Demonstrated 100% specificity in identifying action potential-related calcium transients.

Conclusions:

• Refined spike detection and optimal wavelength selection (1100 nm) enable artifact-free and effective all-optical physiology.
• The optimized approach enhances the translational value of all-optical methods for developing network-based therapies.