Maggiolini Emma, Viaro Riccardo, Franchi Gianfranco
Dipartimento di Scienze Biomediche e Terapie Avanzate, Sezione di Fisiologia umana e Istituto Nazionale di Neuroscienze, Università di Ferrara, 44100 Ferrara, Italy.
Eur J Neurosci. 2008 May;27(10):2733-46. doi: 10.1111/j.1460-9568.2008.06248.x.
After forelimb motor cortex (FMC) damage, the unaffected homotopic motor cortex showed plastic changes. The present experiments were designed to clarify the electrophysiological nature of these interhemispheric effects. To this end, the output reorganization of the FMC was investigated after homotopic area activity was suppressed in adult rats. FMC output was compared after lidocaine-induced inactivation (L-group) or quinolinic acid-induced lesion (Q-group) of the contralateral homotopic cortex. In the Q-group of animals, FMC mapping was performed, respectively, 3 days (Q3D group) and 2 weeks (Q2W group) after cortical lesion. In each animal, FMC output was assessed by mapping movements induced by intracortical microstimulation (ICMS) in both hemispheres (hemisphere ipsilateral and contralateral to injections). The findings demonstrated that in the L-group, the size of forelimb representation was 42.2% higher than in the control group (P < 0.0001). The percentage of dual forelimb-vibrissa movement sites significantly increased over the controls (P < 0.0005). The dual-movement sites occupied a strip of the map along the rostrocaudal border between the forelimb and vibrissa representations. This form of interhemispheric diaschisis had completely reversed, with the recovery of the baseline map, 3 days after the lesion in the contralateral FMC. This restored forelimb map showed no ICMS-induced changes 2 weeks after the lesion in the contralateral FMC. The present results suggest that the FMCs in the two hemispheres interact continuously through predominantly inhibitory influences that preserve the forelimb representation and the border vs. vibrissa representation.
在前肢运动皮层（FMC）受损后，未受影响的同位运动皮层出现了可塑性变化。本实验旨在阐明这些半球间效应的电生理性质。为此，在成年大鼠同位区域活动受到抑制后，对FMC的输出重组进行了研究。比较了利多卡因诱导的对侧同位皮层失活（L组）或喹啉酸诱导的损伤（Q组）后FMC的输出。在Q组动物中，分别在皮层损伤后3天（Q3D组）和2周（Q2W组）进行FMC映射。在每只动物中，通过映射皮层内微刺激（ICMS）在两个半球（注射同侧和对侧半球）诱导的运动来评估FMC输出。研究结果表明，在L组中，前肢代表区的大小比对照组高42.2%（P < 0.0001）。双前肢-触须运动位点的百分比显著高于对照组（P < 0.0005）。双运动位点沿着前肢和触须代表区之间的前后边界占据了地图的一条带。这种半球间失联络的形式在对侧FMC损伤后3天完全逆转，基线地图恢复。在对侧FMC损伤后2周，恢复的前肢地图未显示ICMS诱导的变化。目前的结果表明，两个半球的FMC通过主要是抑制性影响持续相互作用，从而保留前肢代表区以及与触须代表区的边界。
