Search for: All records

This work focuses on creating a controller for the hip joint of a rat using a canonical motor microcircuit. It is thought that this circuit acts to modulate motor neuron activity at the output stage. We first created a simplified biomechanical model of a rat hindlimb along with a neural model of the circuit in a software tool called Animatlab. The canonical motor microcircuit controller was then tuned such that the trajectory of the hip joint was similar to that of a rat during locomotion. This work describes a successful method for hand-tuning the various synaptic parameters and the influence of Ia feedback on motor neuron activity. The neuromechanical model will allow for further analysis of the circuit, specifically, the function and significance of Ia feedback and Renshaw cells. 

Recent developments in markerless tracking software such as DeepLabCut (DLC) allow estimation of skin landmark positions during behavioral studies. However, studies that require highly accurate skeletal kinematics require estimation of 3D positions of subdermal landmarks such as joint centers of rotation or skeletal features. In many animals, significant slippage between the skin and underlying skeleton makes accurate tracking of skeletal configuration from skin landmarks difficult. While biplanar, high-speed X-ray acquisition cameras offer a way to measure accurate skeletal configuration using tantalum markers and XROMM, this technology is expensive, not widely available, and the manual annotation required is time-consuming. Here, we present an approach that utilizes DLC to estimate subdermal landmarks in a rat from video collected from two standard cameras. By simultaneously recording X-ray and live video of an animal, we train a DLC model to predict the skin locations representing the projected positions of subdermal landmarks obtained from X-ray data. Predicted skin locations from multiple camera views were triangulated to reconstruct depth-accurate positions of subdermal landmarks. We found that DLC was able to estimate skeletal landmarks with good 3D accuracy, suggesting that this might be an approach to provide accurate estimates of skeletal configuration using standard live video.