Fuggetta Giorgio, Fiaschi Antonio, Manganotti Paolo
Section of Neurological Rehabilitation, Department of Neurological and Visual Sciences, Gianbattista Rossi Hospital, University of Verona, P.le Scuro, Verona 37134, Italy.
Neuroimage. 2005 Oct 1;27(4):896-908. doi: 10.1016/j.neuroimage.2005.05.013.
Combined transcranial magnetic stimulation/electroencephalography (TMS/EEG) was used to study the activation and interaction of cortical regions to a variety of focused sub- and suprathreshold magnetic pulses over the left primary motor cortex (M1) in ten healthy subjects. Five single-pulse TMS conditions were performed based on the individual resting motor threshold (RMT): (1) 80%; (2) 100%; (3) 120%; (4) 130%; and (5) sham. Simple self-paced movements of the right first finger were also executed. We evaluated the reactions to magnetic stimulation and movement conditions using event-related power and event-related coherence transformations of alpha and beta rhythms. Event-related power reflected regional oscillatory activity of neural assemblies, while event-related coherence reflected the inter-regional functional coupling of oscillatory neural activity. The event-related power transformation revealed that the magnetic pulse modulated cortical oscillations within the first half second for both frequency ranges. For the alpha rhythm, threshold TMS induced a small decrease in the amplitude of EEG oscillations over the stimulation site, while for both rhythms, a progressive synchronization was observed as the intensity of TMS was increased in both hemispheres. Movement onset produced a greater bilateral decrease of power compared with the effects of a magnetic pulse. The event-related coherence revealed that TMS enhanced the electrode connectivity of both hemispheres. Additionally, it was more enhanced within the first 500 ms following stimulation and was seen only for the alpha frequency rhythm. The increase of functional connectivity between cortical areas was minor for magnetic stimulation conditions compared with that for finger movements. The single-pulse TMS over M1 partially modulated the motor cortex generators of oscillatory activity, while a simple active self-paced movement of the right first finger induced greater cortex activation and coupling between cortical regions. We propose that finger movements impose higher functional demands on the motor system compared to artificial magnetic stimulation. These findings are consistent with the possibility that the human motor system may be based on network-like oscillatory cortical activity and might be modulated by brief electromagnetic sub- and suprathreshold pulses applied to M1, suggesting a phenomenon of resetting.
采用联合经颅磁刺激/脑电图(TMS/EEG)技术,研究了10名健康受试者左侧初级运动皮层(M1)对各种聚焦的阈下和阈上磁脉冲的皮质区域激活及相互作用。基于个体静息运动阈值(RMT)进行了5种单脉冲TMS条件:(1)80%;(2)100%;(3)120%;(4)130%;以及(5)假刺激。还执行了右手食指的简单自主运动。我们使用α和β节律的事件相关功率和事件相关相干变换来评估对磁刺激和运动条件的反应。事件相关功率反映了神经集合的区域振荡活动,而事件相关相干反映了振荡神经活动的区域间功能耦合。事件相关功率变换显示,两种频率范围内的磁脉冲在前半秒内调制了皮质振荡。对于α节律,阈下TMS在刺激部位引起脑电图振荡幅度的小幅下降,而对于两种节律,随着TMS强度在两个半球增加,观察到逐渐同步。与磁脉冲的作用相比,运动开始产生了更大的双侧功率下降。事件相关相干显示TMS增强了两个半球的电极连接性。此外,在刺激后的前500毫秒内增强更为明显,并且仅在α频率节律中可见。与手指运动相比,磁刺激条件下皮质区域之间功能连接的增加较小。M1上的单脉冲TMS部分调制了振荡活动的运动皮层发生器,而右手食指的简单自主主动运动诱导了更大的皮层激活和皮质区域之间的耦合。我们提出,与人工磁刺激相比,手指运动对运动系统提出了更高的功能要求。这些发现与人类运动系统可能基于类似网络的振荡皮质活动并且可能受到施加于M1的短暂电磁阈下和阈上脉冲调制的可能性一致,提示了一种重置现象。