Ryun Seokyun, Kim June Sic, Lee Hyeongrae, Chung Chun Kee
Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Sciences, Seoul, 08826, Korea.
Department of Brain & Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, 08826, Korea.
Sci Rep. 2017 Nov 13;7(1):15442. doi: 10.1038/s41598-017-15767-x.
Humans can easily detect vibrotactile stimuli up to several hundred hertz, but underlying large-scale neuronal processing mechanisms in the cortex are largely unknown. Here, we investigated the macroscopic neural correlates of various vibrotactile stimuli including artificial and naturalistic ones in human primary and secondary somatosensory cortices (S1 and S2, respectively) using electrocorticography (ECoG). We found that tactile frequency-specific high-gamma (HG, 50-140 Hz) activities are seen in both S1 and S2 with different temporal dynamics during vibration (>100 Hz). Stimulus-evoked S1 HG power, which exhibited short-delayed peaks (50-100 ms), was attenuated more quickly in vibration than in flutter (<50 Hz), and their attenuation patterns were frequency-specific within vibration range. In contrast, S2 HG power, which was activated much later than that of S1 (150-250 ms), strikingly increased with increasing stimulus frequencies in vibration range, and their changes were much greater than those in S1. Furthermore, these S1-S2 HG patterns were preserved in naturalistic stimuli such as coarse/fine textures. Our results provide persuasive evidence that S2 is critically involved in neural processing for high-frequency vibrotaction. Therefore, we propose that S1-S2 neuronal co-operation is crucial for full-range, complex vibrotactile perception in human.
人类能够轻松检测到高达数百赫兹的振动触觉刺激，但皮层中潜在的大规模神经元处理机制在很大程度上尚不清楚。在此，我们使用皮层脑电图（ECoG）研究了人类初级和次级体感皮层（分别为S1和S2）中各种振动触觉刺激（包括人工和自然主义刺激）的宏观神经相关性。我们发现，在振动（>100Hz）期间，S1和S2中均出现了具有不同时间动态的触觉频率特异性高伽马（HG，50-140Hz）活动。刺激诱发的S1 HG功率呈现出短延迟峰值（50-100ms），在振动中比在颤动（<50Hz）中衰减得更快，并且它们的衰减模式在振动范围内是频率特异性的。相比之下，S2 HG功率比S1激活得晚得多（150-250ms），在振动范围内随着刺激频率的增加而显著增加，并且其变化比S1中的变化大得多。此外，这些S1-S2 HG模式在诸如粗糙/精细纹理等自然主义刺激中得以保留。我们的结果提供了有说服力的证据，表明S2在高频振动触觉的神经处理中起着关键作用。因此，我们提出S1-S2神经元合作对于人类全范围、复杂的振动触觉感知至关重要。
