Waters R S, Li C X, McCandlish C A
Department of Anatomy and Neurobiology, University of Tennessee, College of Medicine, Memphis 38163, USA.
Exp Brain Res. 1995;103(2):183-97. doi: 10.1007/BF00231705.
We studied the organization of the forepaw barrel subfield (FBS) in layer IV of adult rat somatosensory cortex using the mitochondrial marker cytochrome oxidase and related this organization to the representation of the forepaw. The FBS is an ovoid structure consisting of barrels and barrel-like structures, the most conspicuous of which form four centrally located medio lateral running bands. Each band contains three to four barrels. These centrally located bands are bordered along their entire lateral side by a nebulous zone of undifferentiated labeling. At the anterior border, two small barrels are located laterally and one or two larger barrels are located medially. Medial to the central zone are three well-defined barrels. The posterior border consists of a nebulous field of labeling and occasional barrel-like structures. The results from our electrophysiological recording and mapping revealed that the forepaw representation was topographically organized into a single map and that the forepaw map matches almost precisely with individual barrels and barrel-like structures in the FBS. Each of the four central bands is associated with the representation of a single glabrous digit. Digit two (D2) is represented anteriorly and followed posteriorly by D3 through D5. Within each digit band the digit is somatotopically organized, with the skin over the distal phalanx represented in the two lateral barrels and the middle and proximal phalanges represented in the medial barrel(s). The dorsal hairy digit skin and dorsal hand are represented in the lateral zone. D1 is represented by two small anteriorly located barrels. Medial to the representation of the glabrous digits is the representation of the palmar pads. The representation of these pads, in turn, lies between the representations of the thenar (located anteriorly) and hypothenar (located posteriorly) pads. Posterior to the hypothenar pad representation lie the representations of the wrist and forearm. While the present results support the conclusion that individual barrels are associated with discrete locations on the forepaw, examples were found where the recording site was not precisely located within the predicted barrel. Some of these errors may be accounted for by limitations in the mapping techniques; nevertheless, the FBS offers an excellent model system to study relationships between cortical structure and function.
我们使用线粒体标记细胞色素氧化酶研究了成年大鼠体感皮层IV层中前爪桶状亚区（FBS）的组织结构，并将该组织结构与前爪的表征相关联。FBS是一个椭圆形结构，由桶状和桶状样结构组成，其中最明显的形成四条位于中央的、沿中-外侧方向延伸的带。每条带包含三到四个桶状结构。这些位于中央的带在其整个外侧边缘被一个未分化标记的模糊区域所环绕。在前缘，两个小桶状结构位于外侧，一两个较大的桶状结构位于内侧。中央区内侧有三个界限分明的桶状结构。后缘由一个标记模糊的区域和偶尔出现的桶状样结构组成。我们的电生理记录和图谱绘制结果显示，前爪表征在地形上被组织成一个单一图谱，并且前爪图谱几乎与FBS中的单个桶状和桶状样结构精确匹配。四条中央带中的每一条都与单个无毛指的表征相关联。第二指（D2）在前部被表征，其后依次是D3至D5。在每个指带内，指按躯体定位组织，远节指骨上的皮肤在两个外侧桶状结构中被表征，中节和近节指骨在中间的桶状结构中被表征。背侧有毛指皮肤和背侧手部在外侧区被表征。D1由两个位于前部的小桶状结构表征。无毛指表征的内侧是掌垫的表征。这些掌垫的表征又位于鱼际（位于前部）和小鱼际（位于后部）掌垫表征之间。小鱼际掌垫表征的后方是腕部和前臂的表征。虽然目前的结果支持单个桶状结构与前爪上离散位置相关联的结论，但也发现了一些记录位点未精确位于预测桶状结构内的例子。其中一些误差可能是由于图谱绘制技术的局限性造成的；尽管如此，FBS提供了一个研究皮层结构与功能之间关系的优秀模型系统。
