Correlation between patterns of horizontal connectivity and the extent of short-term representational plasticity in rat motor cortex
Correlation between patterns of horizontal connectivity and the extent of short-term representational plasticity in rat motor cortex
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DOI：
10.1093/cercor/7.2.143
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发表时间：
1997-03-01
期刊：
影响因子：
3.7
通讯作者：
Huntley, GW
中科院分区：
文献类型：
--
作者：
Huntley, GW
成人大脑皮层的表征地图的可塑性在感觉和运动皮层都有记录，但皮层可塑性的解剖学基础仍然知之甚少。为了研究初级运动皮层（M1）的水平连接性作为成人运动皮层表征的短期功能可塑性的假定解剖学基底，电刺激和生物胞素标记的组合被用于检查与对侧面神经横断诱导的运动运动图重组模式相关的成年大鼠M1中预先存在的内在连接模式。神经切断后两小时，小，限制区域的前肢代表扩大到领土以前专门的触须代表。在这个新的扩展的前肢区域之外，在测试的几个小时内的任何时间都不能从前触须代表中诱发前肢运动，因此代表沉默的皮层。注射放置到触须皮质代表新扩大的前肢表示引起标记的轴突和密集的终端纤维标记，跨越前肢/触须边界，并延伸到1.2毫米内的低阈值前肢表示。相比之下，注射放置到无声的触须皮层引起标记的轴突和终端扣仍然主要限于原来的触须表示，只有稀疏的预测，进入低阈值前肢表示。因此，这些结果表明，短期内诱导的M1的功能重组周围神经切断后的前几个小时内的程度是介导的，并受到约束，通过预先存在的，水平的投影，横贯代表性的边界的解剖框架。
Plasticity of representational maps in adult cerebral cortex has been documented in both sensory and motor cortex, but the anatomical basis for cortical plasticity remains poorly understood. To investigate horizontal connectivity in primary motor cortex (M1) as a putative anatomical substrate for short-term, functional plasticity of adult motor cortical representations, a combination of electrical stimulation and biocytin labeling was used to examine pre-existing patterns of intrinsic connections in adult rat M1 in relationship to the pattern of reorganization of the motor movement map induced by transection of the contralateral facial nerve. Two hours after nerve cut, small, circumscribed regions of the forelimb representation expanded medially into territory previously devoted to the vibrissae representation. Outside of this novel, expanded forelimb region, no forelimb movement could be evoked from the former vibrissae representation at any time over the period of hours tested, thus representing silent cortex. Injections placed into vibrissae cortex representing the newly expanded forelimb representation gave rise to labeled axons and dense terminal fiber labeling which crossed the forelimb/vibrissae border and extended up to 1.2 mm within the low-threshold forelimb representation. In contrast, injections placed into silent vibrissae cortex gave rise to labeled axons and terminal boutons which remained mostly restricted to the original vibrissae representation, with only sparse projections that crossed into the low-threshold forelimb representation. Thus, these results suggest that the extent of short-term, functional reorganization of M1 induced within the first several hours following peripheral nerve cut is mediated, and constrained, by an anatomical framework of pre-existing, horizontal projections which traverse representation borders.