Research with the NeuroMechatronics Lab at CMU

I currently work as a research intern for the NeuroMechatronics Lab at Carnegie Mellon University. Last semester, I worked mostly on building a neuromuscular model of the arm using MATLAB and Simulink. This semester, I have worked on a mouse-training setup using Arduino, developing a head-fixation system and building a mousewheel, and training in surgeries and procedures for inducing stroke in mice and studying mice post stroke. Below is a more detailed overview of my work.

Neuromuscular Model of the Arm

Using Matlab and Simulink, I worked with Omar Refy and Hazel Cline to build a 2D neuromuscular model of the arm that simulated the effect of spinal cord stimulation on arm movement in stroke patients. By modeling the arm as a combination of 2 revolute joints (shoulder and elbow joints), 3 general bones (ulna/radius, humerus, and scapula/clavicle), and 4 main muscles (pectoralis major, rear deltoid, biceps branchii, and triceps branchii) in Simulink, we were able to develop a model that could learn reaching motions and perform the reaching motions with and without interference from stroke. The model reproduced very similar findings to data from actual stroke patients performing reaching tasks with and without spinal cord stimulation. A paper detailing the model and its findings will be presented by Omar Refy at the 2023 11th International IEEE/EMBS Conference on Neural Engineering.

Path of learned reaching motion from model, with and without spinal cord stimulation.

Mouse Training Setup

In a team of 2, I prototyped an Arduino based training system that teaches mice to push buttons in response to LEDs and records data about task completion. The code for the training system was implemented in Arduino and uses a random number generator to light up one of 3 LEDs (red, white, and green) that indicate an action (red indicates pushing the right force sensor, white indicates do nothing, and green indicates pushing the left force sensor). The system then records data such as the number of training iterations, the correct action, the action performed, and whether the correct action was taken. This system was to be used to train mice to complete the task and then retrain and test mice after they experienced stroke. I worked with Wanyi Wang on this prototype.

Headfixation System and Mouse Wheel

My main focus this semester has been developing and building a head fixation system for mice as well as building a mouse wheel that will be used to study the gait of mice post stroke. The head fixation system and mouse wheel draws from multiple sources, so a special thanks to Dr. Isaac Weaver from Duke University for the head fixation system and to Dr. Richard Warren from Columbia University for the detailed instructions on how to build the KineMouse wheel.

For the head fixation system, I drew from this paper by Dr. Isaac Weaver from Duke University that details a 3D printable head fixation system for mice. I modified the setup by adding adjustable optical posts, and lengthening the 3D printed head mounting hardware.

A finished KineMouse Wheel.

For the mouse wheel, I am currently following instructions on how to build Dr. Richard Warren's KineMouse wheel from Columbia University from this paper. Building the wheel involved laser-cutting spokes, supports, and a mirror from acrylic, cementing polycarbonate to the spokes, and positioning the wheel on the axle. The wheel itself is transparent due to the acrylic and polycarbonate, and the mirror is positioned at a 45 degree angle to allow a camera to capture multiple views of the mouse at once. Once the wheel is finished, I will pair it with my head fixation system on an optical breadboard and it will be used to record the gait of mice who have experienced stroke. I plan to analyze video feed from the wheel and mouse experiments through DeepLabCut, a software package that allows for markerless pose estimation of animals performing tasks .

Mousewheel and Head Fixation System Progress

The mouse wheel is currently in progress, however the head fixation system is finished. The head fixation system can be adjusted to different heights and tightening to hold the head implant that will hold the mouse steady on the wheel. The mouse wheel is about 50% assembled. I have attached the spokes to the axle and spaced the wheel out by 3 inches. Up next is cementing the polycarbonate to the wheel, removing the metal spacers, and attaching the mirror. Below is a video of the head fixation system and mouse wheel in action.

IMG_6025.mov

Side view of mouse wheel and head fixation system.

Top view of mouse wheel and head fixation system.

Below are images of the mouse wheel being built and a video of the mouse wheel rotating.

Building the mouse wheel.

Mouse wheel with spacers.

IMG_6019.mov

Surgeries and Procedures

This semester, I have been training in various surgeries and procedures for mice that will be used in stroke research. So far, I have been trained in how to perform retro-orbital injections as well as transcardiac perfusions. I have also been involved in extracting and slicing the brains of mice and will be learning more about extracting and studying the spinal cords of mice. My training will be used to induce stroke in mice and study mice post-stroke in order to better understand how the motor cortex of the brain is impacted by stroke and how movement is regained post-stroke.

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