Ostapoff E M, Johnson J I, Albright B C
Neuroscience. 1983 May;9(1):107-27. doi: 10.1016/0306-4522(83)90050-7.
The distribution and organization of mechanosensory projections to the cuneate, gracile and external cuneate nuclei were mapped in tree squirrels anesthetized with ketamine and urethane. Tungsten microelectrodes were used to record unit and unit cluster responses to mechanical stimulation. Most responses in the gracile nucleus were to stimulation of skin and hairs of the tail, hind foot and leg, and trunk, in that order going from dorsal to ventral in the nucleus. A similar distribution of responses was found in the cuneate nucleus to stimulation of forelimb, neck and pinna going from dorsomedial to ventrolateral in the nucleus. Some responses to stimulation or movement of subcutaneous tissue were found in the cuneate and gracile nuclei. Responses in the external cuneate were to stimulation of deep-lying tissues in the hand medially, the lower arm centrally and the shoulder and trunk laterally. The pattern of projections in the tree squirrel differed most strikingly from that seen in raccoons and opossums in the relatively small extent of projections from the glabrous skin of the forepaws which were concentrated in a small region near the obex in squirrels. In contrast, there was a large representation of hairy receptive fields located on the forelimb in all regions of the squirrel cuneate nucleus. Otherwise, the somatotopic organization of mechanosensory projections to these dorsal column nuclei in tree squirrels was similar to that reported in other mammals.
在用氯胺酮和乌拉坦麻醉的松鼠中，绘制了向楔束核、薄束核和楔外侧核的机械感觉投射的分布和组织情况。使用钨微电极记录对机械刺激的单位和单位簇反应。薄束核中的大多数反应依次是对尾巴、后足和腿部以及躯干的皮肤和毛发的刺激，在核内从背侧到腹侧呈这种顺序。在楔束核中也发现了类似的反应分布，即对前肢、颈部和耳廓的刺激，在核内从背内侧到腹外侧。在楔束核和薄束核中发现了一些对皮下组织刺激或运动的反应。楔外侧核中的反应是对内侧手部深层组织、中部下臂以及外侧肩部和躯干的刺激。松鼠的投射模式与浣熊和负鼠最显著的不同在于，前爪无毛皮肤的投射范围相对较小，集中在松鼠靠近闩的一个小区域。相比之下，松鼠楔束核的所有区域中，前肢上有毛的感受野有大量代表。否则，松鼠中这些背柱核的机械感觉投射的躯体定位组织与其他哺乳动物中报道的相似。
