Large-scale voltage imaging in behaving mice using targeted illumination.

Area of Science:

• Neuroscience
• Optical Imaging
• Biophysics

Background:

• Genetically encoded voltage indicators allow optical imaging of neural activity.
• Widefield microscopy is crucial for high-speed, large-area neural imaging but suffers from background contamination.
• Existing methods lack optical sectioning, limiting signal clarity.

Purpose of the Study:

• To develop and validate a targeted illumination strategy for widefield voltage imaging.
• To improve signal-to-noise ratio and reduce artifacts in optical recordings.
• To enable simultaneous imaging of numerous neurons over large areas in behaving animals.

Main Methods:

• Implementation of a digital-micromirror-device (DMD)-based targeted illumination system.
• Experimental validation using SomArchon fluorescent voltage indicator in neurons.
• Quantitative analysis of signal contrast, photobleaching, and background cross-contamination.

Main Results:

• Targeted illumination significantly increased SomArchon signal contrast.
• The strategy effectively reduced background cross-contamination.
• Photobleaching was decreased, allowing for longer recording durations.
• Simultaneous imaging of tens of spiking neurons was achieved over minutes in behaving mice.

Conclusions:

• DMD-based targeted illumination is a simple yet effective solution for widefield voltage imaging.
• This approach overcomes limitations of traditional widefield microscopy for large-scale neural recordings.
• The method facilitates high-resolution, large-area optical imaging of neural activity in vivo.