Faggin B M, Nguyen K T, Nicolelis M A
Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
Proc Natl Acad Sci U S A. 1997 Aug 19;94(17):9428-33. doi: 10.1073/pnas.94.17.9428.
The occurrence of cortical plasticity during adulthood has been demonstrated using many experimental paradigms. Whether this phenomenon is generated exclusively by changes in intrinsic cortical circuitry, or whether it involves concomitant cortical and subcortical reorganization, remains controversial. Here, we addressed this issue by simultaneously recording the extracellular activity of up to 135 neurons in the primary somatosensory cortex, ventral posterior medial nucleus of the thalamus, and trigeminal brainstem complex of adult rats, before and after a reversible sensory deactivation was produced by subcutaneous injections of lidocaine. Following the onset of the deactivation, immediate and simultaneous sensory reorganization was observed at all levels of the somatosensory system. No statistical difference was observed when the overall spatial extent of the cortical (9.1 +/- 1.2 whiskers, mean +/- SE) and the thalamic (6.1 +/- 1.6 whiskers) reorganization was compared. Likewise, no significant difference was found in the percentage of cortical (71.1 +/- 5.2%) and thalamic (66. 4 +/- 10.7%) neurons exhibiting unmasked sensory responses. Although unmasked cortical responses occurred at significantly higher latencies (19.6 +/- 0.3 ms, mean +/- SE) than thalamic responses (13. 1 +/- 0.6 ms), variations in neuronal latency induced by the sensory deafferentation occurred as often in the thalamus as in the cortex. These data clearly demonstrate that peripheral sensory deafferentation triggers a system-wide reorganization, and strongly suggest that the spatiotemporal attributes of cortical plasticity are paralleled by subcortical reorganization.
成年期皮质可塑性的发生已通过多种实验范式得到证实。这种现象是仅由皮质内在神经回路的变化产生，还是涉及皮质和皮质下的同步重组，仍存在争议。在此，我们通过在成年大鼠的初级体感皮层、丘脑腹后内侧核和三叉脑干复合体中同时记录多达135个神经元的细胞外活动来解决这个问题，记录时间为皮下注射利多卡因导致可逆性感觉失活之前和之后。失活开始后，在体感系统的所有水平都观察到了即时且同步的感觉重组。比较皮质（9.1±1.2根触须，平均值±标准误）和丘脑（6.1±1.6根触须）重组的总体空间范围时，未观察到统计学差异。同样，在表现出去掩蔽感觉反应的皮质神经元（71.1±5.2%）和丘脑神经元（66.4±10.7%）的百分比方面也未发现显著差异。尽管去掩蔽的皮质反应潜伏期（19.6±0.3毫秒，平均值±标准误）明显高于丘脑反应潜伏期（13.1±0.6毫秒），但感觉传入缺失引起的神经元潜伏期变化在丘脑和皮质中出现的频率相同。这些数据清楚地表明，外周感觉传入缺失会引发全系统的重组，并强烈表明皮质可塑性的时空特征与皮质下重组并行。
