McCurdy M L, Gibson A R, Houk J C
Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013, USA.
Neuroimage. 1992 Aug;1(1):23-41. doi: 10.1016/1053-8119(92)90005-8.
Somatosensory responses of cells in the dorsal accessory olive are suppressed following stimulation of the magnocellular red nucleus. Since the magnocellular red nucleus of the cat does not project directly to the dorsal accessory olive, the present experiments were designed to identify indirect pathways that might mediate suppression of olivary responsiveness. Wheat germ agglutinin-horseradish peroxidase was used to compare the location of magnocellular red nucleus terminals with the locations of cells providing input to the rostral dorsal accessory olive. Cells projecting to forelimb rostral dorsal accessory olive can be divided into two main groups: one group comprises a column of large cells located in the ventral caudal cuneate nucleus extending into lamina VI of C1 and C2, and a second group comprises smaller cells located in the ventral rostral cuneate nucleus. Terminations of fibers originating in the magnocellular red nucleus were found to target both groups of cells projecting to the dorsal accessory olive. Therefore, it is possible that the responsiveness of olivary cells is influenced via these terminations. Stimulation of sensorimotor cortex has also been shown to inhibit olivary responsiveness. Terminations from sensorimotor cortex target the same regions of cells that project to the dorsal accessory olive as those of the magnocellular red nucleus, and a similar, perhaps identical, anatomical substrate may serve to modulate olivary sensitivity by the two descending systems.
刺激大细胞红核后，背侧副橄榄核中细胞的体感反应受到抑制。由于猫的大细胞红核并不直接投射到背侧副橄榄核，因此本实验旨在确定可能介导橄榄核反应性抑制的间接通路。使用小麦胚芽凝集素-辣根过氧化物酶来比较大细胞红核终末的位置与向吻侧背侧副橄榄核提供输入的细胞位置。投射到前肢吻侧背侧副橄榄核的细胞可分为两大组：一组由位于尾侧腹侧楔束核的一列大细胞组成，延伸至C1和C2的VI层，另一组由位于吻侧腹侧楔束核的较小细胞组成。发现起源于大细胞红核的纤维终末靶向投射到背侧副橄榄核的两组细胞。因此，橄榄核细胞的反应性可能通过这些终末受到影响。刺激感觉运动皮层也已被证明可抑制橄榄核反应性。感觉运动皮层的终末靶向投射到背侧副橄榄核的细胞区域，与大细胞红核的终末靶向区域相同，并且一个相似的、可能相同的解剖学底物可能用于通过两个下行系统调节橄榄核的敏感性。
