Jain Neeraj, Qi Hui-Xin, Collins Christine E, Kaas Jon H
National Brain Research Centre, Manesar, Haryana 122050, India, and Department of Psychology, Vanderbilt University, Nashville, Tennessee 37203, USA.
J Neurosci. 2008 Oct 22;28(43):11042-60. doi: 10.1523/JNEUROSCI.2334-08.2008.
Adult brains undergo large-scale plastic changes after peripheral and central injuries. Although it has been shown that both the cortical and thalamic representations can reorganize, uncertainties exist regarding the extent, nature, and time course of changes at each level. We have determined how cortical representations in the somatosensory area 3b and the ventroposterior (VP) nucleus of thalamus are affected by long standing unilateral dorsal column lesions at cervical levels in macaque monkeys. In monkeys with recovery periods of 22-23 months, the intact face inputs expanded into the deafferented hand region of area 3b after complete or partial lesions of the dorsal columns. The expansion of the face region could extend all the way medially into the leg and foot representations. In the same monkeys, similar expansions of the face representation take place in the VP nucleus of the thalamus, indicating that both these processing levels undergo similar reorganizations. The receptive fields of the expanded representations were similar in somatosensory cortex and thalamus. In two monkeys, we determined the extent of the brain reorganization immediately after dorsal column lesions. In these monkeys, the deafferented regions of area 3b and the VP nucleus became unresponsive to the peripheral touch immediately after the lesion. No reorganization was seen in the cortex or the VP nucleus. A comparison of the extents of deafferentation across the monkeys shows that even if the dorsal column lesion is partial, preserving most of the hand representation, it is sufficient to induce an expansion of the face representation.
成年大脑在周围和中枢损伤后会经历大规模的可塑性变化。尽管已经表明皮层和丘脑表征都可以重组，但关于每个水平变化的程度、性质和时间进程仍存在不确定性。我们已经确定了猕猴颈部水平长期单侧背柱损伤如何影响体感区3b和丘脑腹后（VP）核中的皮层表征。在恢复期为22 - 23个月的猴子中，在背柱完全或部分损伤后，完整的面部输入扩展到了3b区去传入的手部区域。面部区域的扩展可以一直向内延伸到腿部和足部表征。在同一只猴子中，丘脑VP核中也发生了类似的面部表征扩展，这表明这两个处理水平都经历了类似的重组。扩展表征的感受野在体感皮层和丘脑中相似。在两只猴子中，我们在背柱损伤后立即确定了大脑重组的程度。在这些猴子中，损伤后3b区和VP核的去传入区域对周围触摸立即失去反应。在皮层或VP核中未观察到重组。对不同猴子去传入程度的比较表明，即使背柱损伤是部分性的，保留了大部分手部表征，也足以诱导面部表征的扩展。
