This study describes cortical recordings in a large animal nerve injury model. We investigated differences in primary somatosensory cortex (S1) hyperexcitability when stimulating injured and uninjured nerves and how different cortical layers contribute to S1 hyperexcitability after spared ulnar nerve injury. We used a multielectrode array to record single-neuron activity in the S1 of ten female Danish landrace pigs. Electrical stimulation of the injured and uninjured nerve evoked brain activity up to 3 h after injury. The peak amplitude and latency of early and late peristimulus time histogram responses were extracted for statistical analysis. Histological investigations determined the layer of the cortex in which each electrode contact was placed. Nerve injury increased the early peak amplitude compared with that of the control group. This difference was significant immediately after nerve injury when the uninjured nerve was stimulated, while it was delayed for the injured nerve. The amplitude of the early peak was increased in layers III–VI after nerve injury compared with the control. In layer III, S1 excitability was also increased compared with preinjury for the early peak. Furthermore, the late peak was significantly larger in layer III than in the other layers in the intervention and control group before and after injury. Thus, the most prominent increase in excitability occurred in layer III, which is responsible for the gain modulation of cortical output through layer V. Therefore, layer III neurons seem to have an important role in altered brain excitability after nerve injury.

这项研究描述了大型动物神经损伤模型中的皮质记录。我们研究了刺激受伤和未受伤神经时初级体感皮层 (S1) 过度兴奋性的差异，以及不同皮质层如何在尺神经幸免损伤后导致 S1 过度兴奋性。我们使用多电极阵列记录了 10 头雌性丹麦地方品种猪 S1 的单神经元活动。对受伤和未受伤的神经进行电刺激可在受伤后 3 小时内诱发大脑活动。提取早期和晚期围刺激时间直方图响应的峰值幅度和潜伏期进行统计分析。组织学研究确定了每个电极触点所在的皮质层。与对照组相比，神经损伤增加了早期峰值幅度。当未受伤的神经受到刺激时，这种差异在神经损伤后立即显着，而对于受伤的神经来说则延迟了。与对照组相比，神经损伤后第 III-VI 层早期峰值的幅度有所增加。在第三层，S1兴奋性也比受伤前的早期峰值有所增加。此外，在损伤前后，干预组和对照组中，第三层的晚期峰值明显大于其他层。因此，兴奋性最显着的增加发生在第三层，它负责通过第五层的皮质输出的增益调节。因此，第三层神经元似乎在神经损伤后大脑兴奋性改变中具有重要作用。