Our goal in initiating these studies was primarily to standardize a protocol for kinematics in mice running on a treadmill. We also wanted to determine whether this assay would allow analysis of the sensory-motor control of locomotion as previously described in cats (Jiang and Drew 1996). Experimental setup and data from one mouse before and after unilateral lesion of the dorsal columns at thoracic level (T-11) are presented in Figures 1 and 2. Briefly:
Main Steps:
- Mark the hip, knee and ankle joints on the right and the left leg (Figure 1).
- Video-tape mice running on treadmill (Figure 1).
- Perform dorsal column lesion at T11 on the right side.
- Allow animals to recover from surgery for 2 days.
- Repeat video recording while running on the treadmill at the same speed as before lesion (Figure 1).
Data Analysis:
- Select video segments for digitization (Figure 2).
- Import video into Peak MotusTM software.
- Auto-trace the reference point and the hip, knee and ankle joints (Figure 2).
- Plot data as changes in angles with respect to time within a step cycle or each other (Figure 2).
EMG recordings:
- Surgically implant a 16-channel surface electrode (Figure 1) under the skin, on top of the thigh muscles as previously described for rats (Biedermann, Schumann et al. 2000).
- Use the Peak MotusTM software for simultaneous kinematics and EMG recordings (Jiang and Drew 1996).

Figure 1: Kinematics setup and a multi-channel surface EMG electrode for evaluating the extensor/flexor muscle function in freely moving mice. A: A 12’X8’ room in our laboratory is houses the kinematics setup. Mice are trained to run on a treadmill (1) with variable speed and incline. The right lane (2) is made of clear Plexiglas. Video tapes (3) of freely moving mice are generated using a high-speed (60 frames/sec) digital camera (4) mounted on a tripod. Quality of the video input is monitored using a hand-held monitor (5). Recorded sessions are replayed, digitized and analyzed using the Peak MotusTM software (6). B: A 16-channel surface EMG electrode (kindly fabricated and provided by Dr. Biedermann; [Biedermann, 2000 #1383]). Sixteen silver balls protrude out of a soft synthetic polymer sheet (1, see C for a magnified view). Each ball is connected to a 16-prong telephone connector (2) though an insulated platinum wire (red). Two blue wires (3) serve as ground.
 

Figure 2: Kinematics analysis in normal mice and comparison with motor performance 2 days after unilateral (right-side) lesion of the dorsal column at the thoracic (T-11) level. A: Thirteen frames from a video-clip representing one step with the computer traced marks (blue) and stick diagram (purple lines). B: A model stick diagram showing the angle measured in panels C and D. C: Coupling of the hip-knee (top), hip-ankle (middle) and knee-ankle (bottom) joints. The traces for pre-lesion (blue, control); post-lesion ipsilateral hind leg (green) and post-lesion contralateral hindleg (red) were generated using the Peak Motus software. For easy interpretation, the flexion-extension code is shown. After unilateral lesion of the dorsal columns, the hip remains more flexed throughout the step cycle (top and middle). Mice compensate the effects of lesion by over-extending the ankle of the contralateral leg. D: Movements of the hip, knee and ankle joints during a step cycle in the normal mice and in the same mouse after the dorsal column lesion on the right side (T11). Note that hip is over-extended after the lesion in both hind legs. The knee and the ankle joints are recruited sooner (compare top panel with the middle and the bottom panels) reducing the stance-phase to less than 50% of the step cycle.

The following recording and movie from a control mouse illustrates how different leg joints are used during locomotion. 
(Please click on the bottom left GO button to play the movie)