Catwalk xt

Noldus CatWalk XT is a gait analysis system for rodents and was used to study differences in walking patterns between different mouse groups. Experiments were set‐up with following parameters: minimum run duration of 0.5 s, maximum run duration of 5 s, maximum allowed speed variation at 60%.
Data were gathered and analyzed using the Noldus CatWalk XT software. Text on Movies [Link], [Link] (genotype) was added using Descript 55.1.1 software.

Prior to study commencement, the Guinea pigs were acclimated to the automated gait analysis walkway (Noldus CatWalk XT, Noldus Information Technology, Netherlands) on the system located in a CRF operating room [10 (link)]. The following week, baseline gait data for all 26 Guinea pigs were obtained over the course of two days. Prior to walking, each animal’s weight was recorded. Gait was recorded using the automated gait analysis walkway system to calculate the locomotion parameters (Table 1). Each animal’s paws were dampened using a water-soaked towel prior to the run so that the system would better identify the prints as the animal walked across the walkway. After the animal left the walkway, a lab member reviewed the data using the system’s “Auto Classify” function to identify each paw print in the trial. Incomplete prints and pauses were excluded from the run. Once classified, the number of step cycles in each run was recorded. Each Guinea pig walked until 15 complete step cycles (15 steps per each limb) had been acquired, which required multiple runs. The number of runs needed to reach 15 step cycles varied between animals, but an average of 4–5 runs was necessary.

The Noldus CatWalk XT gait analysis system (Noldus Information Technology, Leesburg, VA) was used to analyze the paw prints of mice.^{1 (link),22 ,31 (link),33 (link),38 (link)} In a dark room, mice walked across an elevated glass platform with a camera positioned underneath, facing the underside of the animal. Light illuminated the section of the paws that applied weight on the glass (Fig. 1A). Paw prints were imaged by the camera and measured using the Noldus CatWalk XT 10 software (Fig. 1B). The paw print area refers to the total area of the glass in contact with the paw, measured at the point in the step when the area of contact with the glass is maximal for that paw print. Analgesic studies in incision animals were performed in mice that had a relative paw print area in the ipsilateral paw that was no greater than 80% than of the contralateral paw; 10 of 46 mice were thus excluded based on this criterion.

In order to assess the recovery of motor function, a walking track analysis was performed using the CatWalk XT (Noldus Information Technology, the Netherlands). In every animal, three repeated measurements were carried out under constant conditions to record the steadiness of gait. The measurements took place preoperatively as control as well as postoperatively after 1, 2, and 4 weeks as previously described (Kappos et al., 2015). A sciatic functional index (SFI) of 0 is normal. A SFI of ‐ 100 indicates total impairment, such as would result from a complete transection of the sciatic nerve (Cheng et al., 1997; Kanaya, Firrell, Tsai, & Breidenbach, 1992).

A Catwalk system (CatWalk XT, Noldus) was used to assess gait performance in Drd1 cKO or control mice. High-speed camera was mounted beneath the glass platform to record walking patterns. Mice were trained for 3 d to travel from one end of the corridor to the other end and were given 3 trials with a 10-min inter-trial interval on the test day. The recorded videos were analyzed for the average stride length of right forepaw (RF), right hindpaw (RH), left forepaw (LF), and left hindpaw (LH).

Gait analysis was performed using the CatwalkXT (Noldus Information Technology, Netherlands) as described previously (Parvathy and Masocha, 2013 (link)). The green intensity of the walkway was set at 0.10 and camera gain at 20.00. Only runs of 3–12 s duration with speed variances below 80% were considered for analysis, which was performed using the CatwalkXT software.