Simons D J, Durham D, Woolsey T A
Somatosens Res. 1984;1(3):207-45. doi: 10.3109/07367228409144548.
This study was undertaken to determine the functional properties of neurons in the anatomically altered somatosensory cortex after neonatal whisker damage. In mice and rats neonatal lesions of the facial vibrissae change the anatomical organization of barrels in the contralateral SmI cortex. These changes depend on the pattern and severity of the peripheral damage and the developmental age of the animals. To understand some of the functional correlates of these anatomical changes, the middle row of vibrissae (row C) was damaged in mice on postnatal days 1, 3, and 5 and in rats on postnatal days 1 and 5. The receptive field properties of single cortical units were studied after the animals matured. In 24 mice and 15 rats a total of 1,370 units were characterized in microelectrode penetrations which passed through the somatosensory cortex either tangential or perpendicular to the pia. Units were localized anatomically with respect to both barrel and laminar boundaries, and the extent of the peripheral damage was assessed histologically. The data revealed an orderly representation of the sensory periphery that coincided with the altered cytoarchitectonic organization of the SmI cortex. Specifically: (1) Units in the enlarged row B or row D barrels responded primarily to row B or row D whiskers. (2) In layer IV, units in the altered row C cortex either could not be reliably driven from the periphery, were activated by stimulation of scar tissue in the damaged facial row C, or were driven by adjacent, intact row B or row D whiskers. (3) Units in supra- and infragranular layers either had no row C representation or incorporated scar tissue in their receptive fields in a topographically correct fashion. Responses of units to stimulation of scar tissue were qualitatively similar to those elicited from intact vibrissae, which also activated them. (4) In SmII, units that responded to whiskers had receptive fields whose organization matched the representation of the periphery observed in SmI. (5) There was no mapping of nonmystacial pad structures in the barrel cortex, and there were no units with abnormal multiwhisker interactions when laminar boundaries were taken into account. These data indicate that neonatal damage to the whiskers alters both the anatomical arrangement of the barrels and the physiologically determined somatotopic representation of the sensory periphery in a parallel and predictable fashion.
本研究旨在确定新生期触须损伤后，解剖结构改变的体感皮层中神经元的功能特性。在小鼠和大鼠中，面部触须的新生期损伤会改变对侧初级体感皮层（SmI）中桶状结构的解剖组织。这些变化取决于外周损伤的模式和严重程度以及动物的发育年龄。为了解这些解剖学变化的一些功能相关性，在出生后第1天、第3天和第5天的小鼠以及出生后第1天和第5天的大鼠中，损伤了中间一排触须（C排）。在动物成熟后，研究了单个皮层单元的感受野特性。在24只小鼠和15只大鼠中，通过微电极穿刺对总共1370个单元进行了特征描述，这些穿刺穿过体感皮层，与软脑膜呈切线或垂直方向。单元在解剖学上相对于桶状结构和层界进行定位，并通过组织学评估外周损伤的程度。数据显示感觉外周的有序表征与SmI皮层改变的细胞结构组织相吻合。具体而言：（1）扩大的B排或D排桶状结构中的单元主要对B排或D排触须作出反应。（2）在第IV层，改变的C排皮层中的单元要么无法从外周可靠地驱动，要么通过刺激受损面部C排中的瘢痕组织而被激活，要么由相邻的完整B排或D排触须驱动。（3）颗粒上层和颗粒下层中的单元要么没有C排表征，要么在其感受野中以地形正确的方式纳入了瘢痕组织。单元对瘢痕组织刺激的反应在质量上与完整触须引发的反应相似，完整触须也能激活它们。（4）在次级体感皮层（SmII）中，对触须有反应的单元的感受野组织与在SmI中观察到的外周表征相匹配。（5）在桶状皮层中没有非触须垫结构的映射，并且当考虑层界时，没有具有异常多触须相互作用的单元。这些数据表明，新生期触须损伤以平行且可预测的方式改变了桶状结构的解剖排列以及感觉外周的生理确定的躯体定位表征。
