Centre de Recherche Cerveau et Cognition, Université de Toulouse, Toulouse, 31052, France
Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, 3584 CS, The Netherlands.
J Neurosci. 2023 Apr 26;43(17):3107-3119. doi: 10.1523/JNEUROSCI.1758-22.2023. Epub 2023 Mar 17.
Both passive tactile stimulation and motor actions result in dynamic changes in beta band (15-30 Hz Hz) oscillations over somatosensory cortex. Similar to alpha band (8-12 Hz) power decrease in the visual system, beta band power also decreases following stimulation of the somatosensory system. This relative suppression of α and β oscillations is generally interpreted as an increase in cortical excitability. Here, next to traditional single-pulse stimuli, we used a random intensity continuous right index finger tactile stimulation (white noise), which enabled us to uncover an impulse response function of the somatosensory system. Contrary to previous findings, we demonstrate a burst-like initial increase rather than decrease of beta activity following white noise stimulation (human participants, = 18, 8 female). These β bursts, on average, lasted for 3 cycles, and their frequency was correlated with resonant frequency of somatosensory cortex, as measured by a multifrequency steady-state somatosensory evoked potential paradigm. Furthermore, beta band bursts shared spectro-temporal characteristics with evoked and resting-state β oscillations. Together, our findings not only reveal a novel oscillatory signature of somatosensory processing that mimics the previously reported visual impulse response functions, but also point to a common oscillatory generator underlying spontaneous β bursts in the absence of tactile stimulation and phase-locked β bursts following stimulation, the frequency of which is determined by the resonance properties of the somatosensory system. The investigation of the transient nature of oscillations has gained great popularity in recent years. The findings of bursting activity, rather than sustained oscillations in the beta band, have provided important insights into its role in movement planning, working memory, inhibition, and reactivation of neural ensembles. In this study, we show that also in response to tactile stimulation the somatosensory system responds with ∼3 cycle oscillatory beta band bursts, whose spectro-temporal characteristics are shared with evoked and resting-state beta band oscillatory signatures of the somatosensory system. As similar bursts have been observed in the visual domain, these oscillatory signatures might reflect an important supramodal mechanism in sensory processing.
被动触觉刺激和运动动作都会导致躯体感觉皮层的β波段（15-30 Hz）振荡发生动态变化。类似于视觉系统中α波段（8-12 Hz）功率的降低，躯体感觉系统受到刺激后，β波段的功率也会降低。这种α和β振荡的相对抑制通常被解释为皮质兴奋性的增加。在这里，除了传统的单脉冲刺激外，我们还使用了随机强度连续的右食指触觉刺激（白噪声），这使我们能够揭示躯体感觉系统的脉冲响应函数。与先前的发现相反，我们证明了在白噪声刺激后β活动不是减少而是爆发式增加（人类参与者，n=18，女性 8 人）。这些β爆发平均持续 3 个周期，其频率与多频稳态躯体感觉诱发电位范式测量的躯体感觉皮层的共振频率相关。此外，β波段爆发与诱发性和静息状态β振荡具有相似的频谱-时频特征。总之，我们的研究结果不仅揭示了躯体感觉处理的一种新的振荡特征，这种特征类似于先前报道的视觉脉冲响应函数，而且还表明在没有触觉刺激的情况下，自发β爆发和刺激后的锁相同步β爆发存在共同的振荡发生器，其频率由躯体感觉系统的共振特性决定。近年来，对振荡的瞬态性质的研究越来越受到关注。在β波段中发现爆发活动而不是持续振荡，为其在运动规划、工作记忆、抑制和神经集合的重新激活中的作用提供了重要的见解。在这项研究中，我们表明，躯体感觉系统在受到触觉刺激时也会以约 3 个周期的振荡β波段爆发作出反应，其频谱-时频特征与躯体感觉系统的诱发性和静息状态β波段振荡特征相似。由于在视觉领域也观察到了类似的爆发，这些振荡特征可能反映了感觉处理中的一个重要的超模态机制。
