Abstract

Background:

Low-frequency rTMS can induce upregulation of excitability in the contralateral hemisphere by interhemispheric interaction.

Objective:

The aim of this study was to compare the effects of interhemispheric modulation on hemodynamic changes after applying low-frequency rTMS over the anatomical hand knob (HK) and the hand motor hotspot (hMHS) in the dominant motor cortex.

Methods:

Ten healthy right-handed participants without a history of neurological or psychiatric symptoms (five males; 29.8±2.8 years) participated in this single-blind, randomized, cross-over study. rTMS was applied under three conditions over the dominant (left) hemisphere for 20 minutes: 1) 1 Hz rTMS stimulation on the HK (HK-rTMS), 2) 1 Hz rTMS stimulation on the hMHS (hMHS-rTMS), and 3) sham stimulation (Sham-rTMS). For all participants, functional near-infrared spectroscopy (fNIRS) was applied for measurement of cerebral oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) concentration over the non-dominant (right) hemisphere during a serial reaction time task (SRTT) with the non-dominant (left) hand before and after each condition.

Results:

The average coordinates of the hMHS (x = – 39.60 mm, y = – 17.11 mm, z = 66.40 mm) were anterior and lateral to the HK (x = – 36.72 mm, y = – 28.87 mm, z = 56.41 mm). In fNIRS time-series analysis, the integral value of oxyHb was

significantly increased over the motor cortical region of the non-dominant hemisphere after the hMHS-rTMS compared with Sham-rTMS. The HK-rTMS also showed slight increment of oxyHb concentration but without statistical significance. The SPM group analysis showed greater magnitude of the activity in hMHS-rTMS than that of HK-rTMS after stimulation (p < 0.05).

Conclusions:

These results demonstrated an interhemispheric modulation effect of hemodynamic changes by 1 Hz rTMS. The hMHS produced a more robust modulation effect of 1 Hz rTMS on the contralateral hemisphere than did the HK. Therefore, the rTMS can be considered a better stimulation target than the HK.

中文翻译：

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解剖手柄和手部运动热点重复经颅磁刺激后血流动力学变化的比较：功能性近红外光谱研究

摘要

背景：

低频 rTMS 可以通过半球间相互作用诱导对侧半球兴奋性的上调。

客观的：

本研究的目的是比较在解剖手旋钮 (HK) 和主要运动皮层的手部运动热点 (hMHS) 上应用低频 rTMS 后，半球间调制对血流动力学变化的影响。

方法：

10 名没有神经或精神症状病史的健康右手参与者（5 名男性；29.8±2.8 岁）参加了这项单盲、随机、交叉研究。rTMS 在三种条件下应用于优势（左）半球 20 分钟：1）HK (HK-rTMS) 上的 1 Hz rTMS 刺激，2) hMHS (hMHS-rTMS) 上的 1 Hz rTMS 刺激，以及 3)假刺激 (Sham-rTMS)。对于所有参与者，功能性近红外光谱 (fNIRS) 被应用于测量非优势（右）半球的脑氧合血红蛋白 (oxyHb) 和脱氧血红蛋白 (deoxyHb) 在连续反应时间任务 (SRTT) 期间与非在每个条件之前和之后的优势（左）手。

结果：

hMHS 的平均坐标 (x = – 39.60 mm, y = – 17.11 mm, z = 66.40 mm) 位于 HK 的前方和侧面 (x = – 36.72 mm, y = – 28.87 mm, z = 56.41 mm)。在 fNIRS 时间序列分析中，oxyHb 的积分值为

与假-rTMS 相比，hMHS-rTMS 后非优势半球的运动皮层区域显着增加。HK-rTMS 也显示 oxyHb 浓度略有增加，但没有统计学意义。SPM 组分析显示刺激后 hMHS-rTMS 的活性比 HK-rTMS 的活性更大 ( p  < 0.05)。

结论：

这些结果证明了 1 Hz rTMS 对血流动力学变化的半球间调制作用。hMHS 在对侧半球产生了比 HK 更强大的 1 Hz rTMS 调制效果。因此，可以认为 rTMS 是比 HK 更好的刺激目标。