Applying Multichannel Optogenetic System for Epidural Spinal Cord Stimulation in Rats

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optogenetics

Background:

• Epidural spinal cord stimulation can restore hind limb movement in spinalized rats.
• The precise parameters and mechanisms underlying this reactivation are not fully understood.
• Optogenetics offers high spatial resolution and cell-type specificity for mechanistic studies.

Purpose of the Study:

• To develop and evaluate a multichannel optogenetic system for precise spinal cord stimulation in rats.
• To investigate the mechanisms of epidural spinal cord stimulation using optogenetic control.
• To enable in-vivo studies of spinal cord circuits controlling hind limb movement.

Main Methods:

• Designed a multichannel optical fiber bundle (720 fibers, 200 µm diameter, 48x15 matrix) for spinal cord coverage (T13-L2).
• Utilized a laser diode with adjustable projection angles, optimized via a hill-climbing algorithm for maximum power output.
• Developed a spinal cord window for precise fiber bundle placement on the dorsal rat spinal cord.

Main Results:

• Demonstrated the system's capability for in-vivo study of spinal cord stimulation.
• Observed distinct spatial distributions for optogenetically induced tibialis anterior (TA) and medial gastrocnemius (MG) muscle responses.
• Validated the precise control over stimulation location and potential for targeted neural activation.

Conclusions:

• The developed multichannel optogenetic system provides a powerful tool for studying spinal cord function.
• This technique allows for high-resolution investigation into the neural control of locomotion.
• The system facilitates mechanistic understanding of spinal cord stimulation for therapeutic applications.