Figure 2. Locomotor impairment of treadmill locomotion due to blockade of 5‐HT₇ receptors is accompanied by coordination and kinematic changes.

A polar plots, joint angle recordings and stick figures from the pre‐drug condition show the normal locomotor activity. B, the initial effect of the drug (3 min after intrathecal application SB269970, a–d) was a disruption of left–right coordination, and increased cycle duration (b). Movements at the hip and knee joints were reduced (c and d), while movements about the ankle and MTP persisted, but became irregular. C, at 8 min after SB269970 (a–d) the Sol EMG burst was reduced in duration on the left side, and became variable on the right. Both inter‐ and intralimb coordination were disrupted (b), and movement was limited to the ankle and MTP joints (c–d). In B and C the terms swing and stance refer to forward and backward movements about the ankle joint, but without weight support during the stance phase, when the limb was dragging on the treadmill surface. D, recovery was obvious at 35 min after the drug was administered. See text for further details. Abbreviations: lAdd/rAdd, left/right adductor muscle; lSol/rSol, left/right soleus muscle; lTA/rTA, left/right tibialis anterior muscle; lTri/rTri, left/right triceps brachii muscle.