Motor Behavioral Analysis: Cylinder Test, Rotarod Test, and Locomotor Activity

Spontaneous forelimb use was assessed in the cylinder test [29]. The rats were placed in a glass cylinder (20 cm in diameter), and forelimb use was analyzed by videotaping the animals as they moved freely in the cylinder and explored the environment. Mirrors were placed behind the cylinder to allow observation of the animals when they were turned away from the camera. An observer blinded to the identity of the animals scored the number of forelimb contacts with the cylinder wall. In rats with unilateral dopaminergic denervations, forelimb asymmetry is expressed as the use of the impaired paw and expressed as the percentage of the total number of touches (20 touches were counted for each animal). An unbiased control animal would thus receive a score of 50%, whereas lesions usually reduce performance of the impaired paw in this test.

Our original rotarod test [30, 31] was performed with slight modifications [32], using an automated 4-lane rotarod unit (CR-1 Rotamex System, Columbus Instruments, Columbus, OH). A session protocol with an accelerated rotational speed was used. Animals were pretrained during 2 consecutive days to reach a stable performance in the test. For rotarod testing, the rats were placed on the rod at an initial speed of 4 rpm. Then, the rod speed was increased to 44 rpm over 90 s, and the total running time on the rod was recorded. In all cases, tests were performed on 3 consecutive days, and the results were averaged to obtain a single value for each rat. Finally, integrated measures for the rotarod performance of each rat were obtained as the area under the curve (AUC).

Spontaneous locomotor activity was automatically monitored with the aid of a Videomex-X motion analyzer (Columbus Instruments), which is a video-based apparatus that monitors the video image in real time (20 frames per second) [33]. The multiple motion monitor software option was used to estimate total activity (rate of motion) of each group of animals. The rate of motion consists of the amount that the picture changes from 1 frame to the next. The program counts the number of pixel changes caused by the movements of all the animals in the picture. Each group of animals was acclimatized to the Videomex for at least 10 min, and locomotor activity was monitored for 30 min. All trials were carried out in a black-walled open-topped box of 70 × 75 × 40 cm. Data obtained from 3 consecutive days were used for the analysis and expressed as percentage of the control group.