Pavey Nathan, Menon Parvathi, van den Bos Mehdi A J, Kiernan Matthew C, Vucic Steve
Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, NSW, Australia.
Brain and Mind Centre, University of Sydney, NSW, Australia.
Neurosci Lett. 2023 Apr 23;803:137191. doi: 10.1016/j.neulet.2023.137191. Epub 2023 Mar 15.
A complex interaction of inhibitory and facilitatory interneuronal processes may underlie development of cortical excitability in the human motor cortex. To determine whether distinct interneuronal processes mediated cortical excitability, threshold tracking transcranial magnetic stimulation was utilised to assess cortical excitability, with figure-of-eight coil oriented in posterior-anterior (PA), anterior-posterior (AP) and latero-medial (LM) directions. Motor evoked potential (MEP) responses were recorded over the contralateral abductor pollicis brevis. Resting motor threshold (RMT), short interval intracortical inhibition (SICI), short interval intracortical facilitation (SICF) and intracortical facilitation were recorded. Significant effects of coil orientation were evident on SICI (F = 8.560, P = 0.002) and SICF (F = 7.132, P = 0.003). SICI was greater when recorded with PA (9.7 ± 10.9%, P = 0.029) and AP (13.1 ± 7.0%, P = 0.003) compared to LM (5.2 ± 7.3%) directed currents. SICF was significantly greater with PA (-14.7 ± 8.1%, P = 0.016) and LM (-14.7 ± 8.8%, P = 0.005) compared to AP (-9.1 ± 7.2%) coil orientations. SICI recorded with LM and PA coil orientations were correlated (R = 0.7, P = 0.002), as was SICF recorded with AP vs LM (R = 0.60, P = 0.019) and LM vs PA (R = 0.69, P = 0.002) coil orientations. RMT was significantly smaller with PA compared to AP (P < 0.001) and LM (P = 0.018) stimulation. Recruitment of distinct interneuronal processes with variable cortical orientation and thresholds underlies short interval intracortical inhibition and facilitation.
抑制性和易化性中间神经元过程的复杂相互作用可能是人类运动皮层皮质兴奋性发展的基础。为了确定不同的中间神经元过程是否介导皮质兴奋性，利用阈值跟踪经颅磁刺激来评估皮质兴奋性，使用八字形线圈分别沿后 - 前（PA）、前 - 后（AP）和外侧 - 内侧（LM）方向放置。在对侧拇短展肌上记录运动诱发电位（MEP）反应。记录静息运动阈值（RMT）、短间隔皮质内抑制（SICI）、短间隔皮质内易化（SICF）和皮质内易化。线圈方向对SICI（F = 8.560，P = 0.002）和SICF（F = 7.132，P = 0.003）有显著影响。与LM（5.2±7.3%）方向的电流相比，当用PA（9.7±10.9%，P = 0.029）和AP（13.1±7.0%，P = 0.003）方向记录时，SICI更大。与AP（-9.1±7.2%）线圈方向相比，PA（-14.7±8.1%，P = 0.016）和LM（-14.7±8.8%，P = 0.005）方向的SICF显著更大。用LM和PA线圈方向记录的SICI具有相关性（R = 0.7，P = 0.002），用AP与LM（R = 0.60，P = 0.019）以及LM与PA（R = 0.69，P = 0.002）线圈方向记录的SICF也具有相关性。与AP（P < 0.001）和LM（P = 0.018）刺激相比，PA刺激时RMT显著更小。不同的中间神经元过程在不同皮质方向和阈值下被募集，这是短间隔皮质内抑制和易化的基础。
