Kolarik R C, Rasey S K, Wall J T
Department of Anatomy, Medical College of Ohio, Toledo 43699.
J Neurosci. 1994 Jul;14(7):4269-88. doi: 10.1523/JNEUROSCI.14-07-04269.1994.
The somatosensory cortex of primates contains patch- and bandlike aggregates of neurons that are dominantly activated by cutaneous inputs from the radial, median, and ulnar nerves to the hand. In the present study, the area 3b hand cortex of adult monkeys was mapped immediately before and after combined median and ulnar nerve transection to evaluate the consistency, extent, and location of early post-injury alterations in the deprived median and ulnar nerve cortical bands. Several alterations were observed acutely after injury. (1) The patchlike cortical aggregates of intact radial nerve inputs from the hand underwent a two- to three-fold expansion. This expansion was not related to peripheral changes in the radial nerve skin territory, but was due to rapid central decompression of radial nerve dominance patches. (2) The largest changes involved patches in lateral to central locations of the hand map. (3) The expanded patches occupied cortical zones that were activated by inputs from the digits, palm, and posterior hand prior to injury. These receptive field shifts were initiated within minutes after injury. (4) Receptive fields of neurons within expanded radial nerve patches were normal in size. (5) Besides changes involving radial nerve inputs from the hand, there was a small expansion of forelimb inputs into the preinjury hand cortex; however, the representation of face inputs did not expand into this cortex. (6) Finally, neurons across 50-69% of the hand cortex were unresponsive to tactile stimuli acutely after this injury. These findings indicate that the distribution patterns of nerve dominance aggregates in adult primates begin changing within minutes after nerve injury. Cortical changes involving specific inputs occupy similar extents and locations of cortex, and are arranged in highly consistent patterns, in different individuals. It is suggested that this consistency reflects specific patterns of central sensitization or disinhibition that are triggered by the injury.
灵长类动物的体感皮层包含斑块状和带状的神经元聚集区，这些区域主要由来自手部桡神经、正中神经和尺神经的皮肤输入激活。在本研究中，在成年猴子的正中神经和尺神经联合横断之前和之后，对其3b区手部皮层进行了图谱绘制，以评估在被剥夺的正中神经和尺神经皮质带中，损伤后早期改变的一致性、范围和位置。损伤后急性观察到了几种改变。（1）来自手部完整桡神经输入的斑块状皮质聚集区扩大了两到三倍。这种扩大与桡神经皮肤区域的外周变化无关，而是由于桡神经优势斑块的快速中枢减压。（2）最大的变化涉及手部图谱中从外侧到中央位置的斑块。（3）扩大的斑块占据了损伤前由手指、手掌和手后部的输入激活的皮质区域。这些感受野的转移在损伤后几分钟内就开始了。（4）扩大的桡神经斑块内神经元的感受野大小正常。（5）除了涉及来自手部桡神经输入的变化外，前肢输入向损伤前手部皮层有少量扩大；然而，面部输入的表征并未扩展到该皮层。（6）最后，在这种损伤后急性情况下，手部皮层50%至69%的神经元对触觉刺激无反应。这些发现表明，成年灵长类动物神经优势聚集区的分布模式在神经损伤后几分钟内就开始发生变化。涉及特定输入的皮质变化在不同个体中占据相似的皮质范围和位置，并以高度一致的模式排列。有人认为，这种一致性反映了由损伤触发的中枢敏化或去抑制的特定模式。
