Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Neuroimage. 2010 May 15;51(1):412-20. doi: 10.1016/j.neuroimage.2010.02.001. Epub 2010 Feb 10.
Induced gamma activity has a key role in the temporal binding of distributed cortico-cortical processing. To elucidate the neural synchronization in the early-stage somatosensory processing, we studied the functional connectivity between the primary and secondary somatosensory cortices (SI and SII) in healthy subjects using magnetoencephalography (MEG) with excellent spatiotemporal resolution. First, somatosensory-evoked magnetic fields were recorded to determine the locations of each cortical activity. Then we analyzed the phase-locking values (PLVs) of the induced gamma activity to assess neural synchrony within the somatosensory cortical network. We also assessed PLVs in patients with multiple sclerosis (MS) to validate our PLV analysis in evaluating the inter-areal functional connectivity, which can often be impaired in MS. The PLVs of the induced gamma activity were calculated for each pair of unaveraged MEG signals that represented the activities of the contralateral SI and bilateral SII areas. Analysis of PLVs between the SI and SII areas showed significantly increased PLVs for gamma-band activities, starting at an early post-stimulus stage in normal controls, whereas this increase in PLVs was apparently diminished in MS. The PLV analysis provided evidence for early-latency, gamma-band neuronal synchronization between the SI and SII areas in normal controls. Our study first demonstrates the gamma-band synchrony in the early-stage human somatosensory processing.
诱发的伽马活动在分布式皮质-皮质处理的时间绑定中起着关键作用。为了阐明早期体感处理中的神经同步，我们使用具有出色时空分辨率的脑磁图 (MEG) 研究了健康受试者中初级和次级体感皮层 (SI 和 SII) 之间的功能连接。首先，记录体感诱发电场以确定每个皮质活动的位置。然后，我们分析了诱导伽马活动的锁相值 (PLV)，以评估体感皮质网络内的神经同步。我们还评估了多发性硬化症 (MS) 患者的 PLV，以验证我们的 PLV 分析在评估区域间功能连接方面的有效性，而 MS 中经常会出现这种功能连接受损的情况。为代表对侧 SI 和双侧 SII 区域活动的未平均 MEG 信号的每一对计算诱导伽马活动的 PLV。对 SI 和 SII 区域之间的 PLV 分析表明，正常对照中在刺激后早期开始出现伽马波段活动的 PLV 显著增加，而 MS 中这种 PLV 的增加明显减少。PLV 分析为正常对照中 SI 和 SII 区域之间的早期潜伏期、伽马波段神经元同步提供了证据。我们的研究首次证明了正常人类体感处理中的早期伽马波段同步。
