Imaging large-scale neural activity with cellular resolution in awake, mobile mice

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optical Imaging

Background:

• Studying brain activity in awake, behaving animals is crucial for understanding neural function.
• Motion artifacts from animal movement are a significant challenge in high-resolution in vivo imaging.
• Existing techniques often require deep anesthesia or limit behavioral paradigms.

Purpose of the Study:

• To develop and validate a robust technique for cellular-resolution two-photon fluorescence imaging in awake, behaving mice.
• To minimize motion artifacts during imaging of neural activity in freely moving subjects.
• To enable the study of behavior-correlated neural dynamics with high fidelity.

Main Methods:

• Utilized an upright, table-mounted two-photon microscope combined with a spherical treadmill system.
• Head-restrained mice with cranial windows ran on an air-supported Styrofoam ball, maintaining head stability.
• Implemented a custom Hidden Markov Model-based algorithm for post-processing motion correction.

Main Results:

• Achieved cellular resolution two-photon imaging in awake, behaving mice with minimal motion artifact (2-5 microm).
• Demonstrated that running-induced brain motion was predominantly in-plane, facilitating motion correction.
• Successfully measured behaviorally correlated calcium transients from neuronal and astrocytic populations with <5% false positive error rate.

Conclusions:

• The developed spherical treadmill system effectively stabilizes the head for high-resolution in vivo imaging in awake, behaving mice.
• This technique significantly reduces motion artifacts, enabling reliable measurement of neural activity during naturalistic behaviors.
• The method provides a powerful tool for investigating the neural basis of behavior with unprecedented detail.