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Updated: Jun 17, 2025
In vivo Optogenetic Stimulation of the Rodent Central Nervous System
Published on: January 15, 2015
Using DeepLabCut-Live to probe state dependent neural circuits of behavior with closed-loop optogenetic stimulation
Melissa Gonzalez1,2,3, Mark A Gradwell1,2, Joshua K Thackray1,2,4
1Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, United States of America.
Background:
Closed-loop behavior paradigms enable us to dissect the state-dependent neural circuits underlying behavior in real-time. However, studying context-dependent locomotor perturbations has been challenging due to limitations in molecular tools and techniques for real-time manipulation of spinal cord circuits.
New Method:
We developed a novel closed-loop optogenetic stimulation paradigm that utilizes DeepLabCut-Live pose estimation to manipulate primary sensory afferent activity at specific phases of the locomotor cycle in mice. A compact DeepLabCut model was trained to track hindlimb kinematics in real-time and integrated into the Bonsai visual programming framework. This allowed an LED to be triggered to photo-stimulate sensory neurons expressing channelrhodopsin at user-defined pose-based criteria, such as during the stance or swing phase.
Results:
Optogenetic activation of nociceptive TRPV1+ sensory neurons during treadmill locomotion reliably evoked paw withdrawal responses. Photoactivation during stance generated a brief withdrawal, while stimulation during swing elicited a prolonged response likely engaging stumbling corrective reflexes.
Comparison With Existing Methods:
This new method allows for high spatiotemporal precision in manipulating spinal circuits based on the phase of the locomotor cycle. Unlike previous approaches, this closed-loop system can control for the state-dependent nature of sensorimotor responses during locomotion.
Conclusions:
Integrating DeepLabCut-Live with optogenetics provides a powerful new approach to dissect the context-dependent role of sensory feedback and spinal interneurons in modulating locomotion. This technique opens new avenues for uncovering the neural substrates of state-dependent behaviors and has broad applicability for studies of real-time closed-loop manipulation based on pose estimation.
