Steeves J D, Sholomenko G N, Webster D M
Brain Res. 1987 Jan 20;401(2):205-12. doi: 10.1016/0006-8993(87)91406-5.
The initiation and control of spinal locomotor mechanisms by supraspinal brainstem centers has been studied in many vertebrate species. However there is very little information regarding brainstem-spinal pathways involved in avian locomotion. To undertake these studies, birds (geese or ducks) were placed in a stereotaxic frame and decerebrated under halothane anesthesia. After anesthesia was discontinued, discrete brainstem regions were electrically stimulated. Locomotion could be evoked from several areas within the pontomedullary reticular formation. The stimulus threshold for evoking walking ranged from 25-50 microA at 30-80 Hz (pulse duration 0.5 ms). At slightly higher current strengths (50-100 microA) wing flapping ('flying') was initiated. Histological examination of the stimulation sites indicated that the predominant locomotor areas were restricted to the ventromedial gigantocellular reticular formation and a more dorsolateral location within the parvocellular reticular formation. To ascertain whether neurons in these regions of the avian brainstem project directly to the spinal cord, a retrograde fluorescent tracer dye, True blue, was injected into either the cervical or low thoracic spinal cord. Comparing the positions of the retrogradely labeled neurons and the effective locomotor stimulation sites indicated a high degree of overlap. The present results, when compared with previous studies, suggest strong similarities in descending brainstem control of locomotion for all vertebrates.
许多脊椎动物物种都对脊髓上脑干中枢对脊髓运动机制的启动和控制进行了研究。然而，关于参与鸟类运动的脑干 - 脊髓通路的信息却非常少。为了进行这些研究，将鸟类（鹅或鸭）置于立体定位框架中，并在氟烷麻醉下进行大脑切除。停止麻醉后，对离散的脑干区域进行电刺激。在脑桥延髓网状结构的几个区域可以诱发运动。诱发行走的刺激阈值在30 - 80Hz（脉冲持续时间0.5ms）时为25 - 50微安。在稍高的电流强度（50 - 100微安）下会引发翅膀扇动（“飞行”）。对刺激部位的组织学检查表明，主要的运动区域局限于腹内侧巨细胞网状结构以及小细胞网状结构内更靠背外侧的位置。为了确定鸟类脑干这些区域的神经元是否直接投射到脊髓，将一种逆行荧光示踪染料真蓝注入颈段或胸段低位脊髓。比较逆行标记神经元的位置和有效的运动刺激部位，发现有高度重叠。与先前的研究相比，目前的结果表明所有脊椎动物在脑干对运动的下行控制方面有很强的相似性。
