Dancause Numa, Barbay Scott, Frost Shawn B, Zoubina Elena V, Plautz Erik J, Mahnken Jonathan D, Nudo Randolph J
Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 673, Rochester, NY 14642, USA.
J Neurophysiol. 2006 Dec;96(6):3506-11. doi: 10.1152/jn.00792.2006. Epub 2006 Sep 20.
After a cortical lesion, cortical areas distant from the site of injury are known to undergo physiological and anatomical changes. However, the mechanisms through which reorganization of distant cortical areas is initiated are poorly understood. In a previous publication, we showed that the ventral premotor cortex (PMv) undergoes physiological reorganization after a lesion destroying the majority of the primary motor cortex (M1) distal forelimb representation (DFL). After large lesions destroying >50% of the M1 DFL, the PMv DFL invariably increased in size, and the amount of the increase was positively correlated with the size of lesion. To determine whether lesions destroying <50% of the M1 DFL followed a similar trajectory, we documented PMv reorganization using intracortical microstimulation techniques after small, ischemic lesions targeting subregions within the M1 DFL. In contrast to earlier results, lesions resulted in a reduction of the PMv DFL regardless of their location. Further, because recent anatomical findings suggest a segregation of PMv connectivity with M1, we examined two lesion characteristics that may drive alterations in PMv physiological reorganization: location of the lesion with respect to PMv connectivity and relative size of the lesion. The results suggest that after a lesion in the M1 DFL, the induction of representational plasticity in PMv, as evaluated using intracortical microstimulation, is related more to the size of the lesion than to the disruption of its intracortical connections.
在皮质损伤后，已知远离损伤部位的皮质区域会发生生理和解剖学变化。然而，引发远处皮质区域重组的机制却鲜为人知。在之前的一篇论文中，我们表明，在损伤破坏了大部分初级运动皮质（M1）的远端前肢代表区（DFL）后，腹侧运动前皮质（PMv）会发生生理重组。在大型损伤破坏了超过50%的M1 DFL后，PMv DFL的大小总是会增加，且增加的幅度与损伤的大小呈正相关。为了确定破坏小于50%的M1 DFL的损伤是否遵循类似的轨迹，我们在针对M1 DFL内各亚区域的小面积缺血性损伤后，使用皮质内微刺激技术记录了PMv的重组情况。与早期结果相反，无论损伤位于何处，都会导致PMv DFL减小。此外，由于最近的解剖学研究结果表明PMv与M1的连接存在分离，我们研究了两个可能驱动PMv生理重组改变的损伤特征：损伤相对于PMv连接的位置以及损伤的相对大小。结果表明，在M1 DFL发生损伤后，使用皮质内微刺激评估的PMv中代表性可塑性的诱导，更多地与损伤的大小有关，而非与皮质内连接的破坏有关。
