Fig. 2.

Bilateral striatal injection of 6-OHDA reduces locomotor activity in the open-field arena. (A–D) Locomotor activity recorded from above in the open-field arena during a single trial of 4.5 min before and after bilateral striatal injection of vehicle (A and B) or 6-OHDA (C and D). The blue point illustrates the animal’s position at the beginning of the trial. (E–I) Comparison of locomotor parameters in the open-field arena in six animals injected in the striatum with vehicle (Veh) and five animals injected with 6-OHDA (6-OH) (seven trials recorded per animal). (E) Time spent in locomotion (i.e., total time duration during which locomotor speed is higher than 3 cm/s for at least 0.5 s). (F) Number (N) of locomotor initiations (i.e., number of times when speed is higher than 3 cm/s for at least 0.5 s). (G) Locomotor speed in centimeters per second. (H) Locomotor bout duration (i.e., time duration during which locomotor speed is higher than 3 cm/s for at least 0.5 s). (I) Time spent immobile, with immobility defined as total time without locomotion. (J–N) Linear relationships between the striatal optical density of TH immunofluorescence and the locomotor parameters described in E–I. For each fit, the coefficient of correlation (R), its significance (P), and the CIs (gray) are illustrated. Mice injected with vehicle appear as green circles; those injected with 6-OHDA as orange circles. *P < 0.05, **P < 0.01, paired tests; ⁺⁺P < 0.01, ⁺⁺⁺P < 0.001, t tests.