SYNCHRONIZED MARKER-BASED 3D MOTION CAPTURE AND CEREBELLAR NUCLEI CALCIUM IMAGING IN FREELY BEHAVING MICE

In our previous studies, we developed a marker-based 3D motion capture system to evaluate movement trajectories during various behaviors and pharmacological treatments in mice. In the present study, we aimed to synchronize these highly accurate behavioral recordings with calcium imaging of neuronal activity in cerebellar nuclei. We used adult male C57BL/6J mice in a within-subject, randomized design (n=6-10). We recorded voluntary behavior in mice at the ages of 3 and 18 months. Mice were implanted with permanent markers located on the hips, lumbar spine, shoulder blades, hindlimb knees, and ankles. We used nVoke 2.0 (Inscopix, CA) miniscope to image cerebellar nuclei (-6.12AP, +/-2L/M, -2D) with GRIN lens covered with virus pAAV.syn.GCaMP6f.WPRE.SV40. A high-speed, high-resolution 3D motion capture system (Qualisys, Sweden) was used to track 3D trajectories and velocity of markers during locomotory tasks: novel environment exploration, vertical climbing, 3D exploration, and running on a treadmill (1 m/min to 40 m/min, doubled with each trial until failure). The brain implants had minor effects on behavior, and they did not decrease the average maximum speed of mice running on the treadmill. Age also did not decrease the ability of mice to run at high speeds, but their step kinematics was significantly affected in the aged mice. Pharmacological treatments had profound effects on movement parameters. Neuronal recordings indicated task-specific, distinct neuronal activity. Further data analysis is ongoing to uncover links between accurate behavioral recordings and neuronal activity.