Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
Neuropsychologia. 2011 Jun;49(7):1928-37. doi: 10.1016/j.neuropsychologia.2011.03.020. Epub 2011 Mar 29.
Damage to the dorsolateral prefrontal cortex (DLPFC) impairs gating of irrelevant sensory information at early cortical processing stages. We investigated how transient inhibition of DLPFC impacts early event-related potentials (ERPs) arising from relevant or irrelevant vibrotactile stimuli to the fingertips. Specifically, we hypothesized that suppression of DLPFC using continuous theta burst stimulation (cTBS) would result in reduced attention-based modulation of tactile ERPs generated at early stages of cortical somatosensory processing. Participants received vibrotactile stimulation to the second and fifth digit on the left hand and reported target stimuli on one digit only (as instructed) in one of three groups following: (1) cTBS over DLPFC (40s; 600 pulses of 3 stimuli at 50 Hz repeated at 5 Hz using 80% of resting motor threshold for abductor pollicis brevis), (2) sham stimulation, or (3) no stimulation. ERP amplitudes for the P50, N70, P100, N140 and long latency positivity (LLP) were quantified for attended and non-attended trials at C4, CP4, and CP3 electrodes. There was no effect of attention on the P50 and N70 however the P100, N140 and LLP were modulated with attention. The P100 and LLP were significantly more positive during trials where the stimuli were attended to, while the N140 was enhanced for non-attended stimuli. Comparisons between groups revealed a reduction in P100 attention-based modulation for the cTBS group versus sham and no-stimulation groups. While the P100 was clearly reduced for non-attended stimuli relative to attended stimuli in the sham and no-stimulation groups, this effect was attenuated following cTBS. The reduction in attentional modulation of the P100 following cTBS suggests that the DLPFC contributes to filtering irrelevant somatosensory information at early cortical processing stages. Notably the influence of the DLPFC in attention-based modulation was evident even within digits of the same hand. The present results support the use of cTBS as an effective means of transiently suppressing DLPFC excitability.
背外侧前额叶皮层（DLPFC）的损伤会损害早期皮质处理阶段无关感觉信息的门控。我们研究了使用连续 theta 爆发刺激（cTBS）短暂抑制 DLPFC 如何影响来自指尖相关或不相关振动触觉刺激的早期事件相关电位（ERP）。具体来说，我们假设使用连续 theta 爆发刺激（cTBS）抑制 DLPFC 会导致在皮质体感加工早期阶段产生的触觉 ERP 的基于注意的调制减少。参与者接受左手第二和第五指的振动触觉刺激，并按照以下三种组之一仅报告一个手指上的目标刺激（根据指示）：（1）DLPFC 上的 cTBS（40s；3 个刺激的 600 个脉冲以 50 Hz 重复，以 80%的伸拇指短肌静息运动阈值使用 5 Hz），（2）假刺激，或（3）无刺激。在 C4、CP4 和 CP3 电极上，对注意和非注意试验的 P50、N70、P100、N140 和长潜伏期正性（LLP）的 ERP 幅度进行了量化。然而，注意对 P50 和 N70 没有影响，但 P100、N140 和 LLP 与注意一起被调制。在注意到刺激的试验中，P100 和 LLP 更积极，而 N140 则增强了非注意刺激。与假刺激和无刺激组相比，cTBS 组的 P100 基于注意的调制减少。虽然在假刺激和无刺激组中，与注意刺激相比，非注意刺激的 P100 明显减少，但在 cTBS 后，这种效应减弱。cTBS 后 P100 注意调制的减少表明 DLPFC 有助于在早期皮质处理阶段过滤无关的体感信息。值得注意的是，即使在同一手的手指中，DLPFC 在基于注意的调制中的影响也是明显的。本研究结果支持使用 cTBS 作为暂时抑制 DLPFC 兴奋性的有效手段。
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