抄録
There are two specific areas identified as supraspinal locomotion-inducing sites in cats: the mesencephalic locomotor region (MLR) in the midbrain and the cerebellar locomotor region (CLR) in the cerebellum. This study aimed to identify supraspinal sites which are involved in evoking hindlimb hopping movements in decerebrate rabbits. Under halothane anesthesia, rabbits (JW, 2-3 kg, ♂) were surgically decerebrated at the precollicular-postmammillary level. The head was then fixed in a stereotaxic apparatus, and the abdominal part was hung up by rubber belts. Pairs of insulated copper wires were inserted into the left and right hindlimb extensors and flexors for EMG recording. Wood's-metal-filled glass microelectrodes were inserted systematically into the midbrain (left side, L1-5) and cerebellum (L3-R3), and electrical stimuli (50 Hz, 10-100 μA, 0.2 ms duration) were applied for 5-10 sec at every 0.5 mm vertically and horizontally. Effective stimulus sites for evoking hindlimb hopping were found in the lateral portion of the midbrain and the midline region of the cerebellar white matter. Histologically, these two sites corresponded to the MLR and CLR identified in cats, respectively. During stimulation to these sites, the left and right hindlimbs exhibited rhythmic hopping movements in phase, not alternately as usually seen in cats' locomotion. These findings suggest that although cats and rabbits have similar locomotion-inducing sites at the supraspinal level, the neural systems for generating their specific locomotor patterns are organized in a different manner in the spinal cord. [Jpn J Physiol 54 Suppl:S184 (2004)]
