不同强度电刺激诱发丘脑激活的功能磁共振成像

Functional MRI study on thalamus activation induced by electrical stimulation of different intensities

目的:采用功能磁共振成像技术(functional magnetic resonance imaging,fMRI)研究受试者在不同强度电刺激作用下丘脑各亚区的激活规律,探讨该区参与痛觉调控的机制。方法:对10名健康右利手志愿者分别施加1倍痛阈、2倍痛阈、3倍痛阈3个不同强度的电刺激任务,同期采用GE1.5T超导型磁共振扫描系统进行全脑fMRI扫描,应用功能性神经图像分析(analysis of functional neuroimages,AFNI)软件包对原始数据进行后处理以获得丘脑活动的脑功能图像。结果:双侧丘脑外侧部的激活信号与刺激强度基本呈线性正相关,提示该区可能与痛觉的感觉辨别方面有关;双侧丘脑内侧部的激活信号(BOLD信号)与刺激强度类似于指数关系,提示该区可能参与痛觉的注意与情绪活动。同时,在相同强度电刺激作用下,对侧丘脑外侧部的激活信号均强于同侧丘脑外侧部,表现出对侧优势现象,而双侧丘脑内侧部则缺乏此表现。结论:丘脑应为痛觉调控网络中的重要组成部分,该区表现出分离性激活现象,各亚区均有各自独特的刺激反应特性,这有助于了解丘脑在处理痛觉信息时所发挥的作用。

Objective To detect the activation pattern of the thalamus in human by the functional magnetic resonance imaging （fMRI） with the electrical stimulation of different intensities, and to explore the mechanism of this area in pain modulation. Methods Ten healthy right-handed volunteers were given different electrical stimulations of 1-, 2-, and 3- times pain threshold respectively, The whole-brain was scanned simultaneously by GE 1, 5 T magnetic resonance imaging system, The data were postprocessed by analysis of functional neuroimages （AFNI） to establish the regional activity maps of the thalamus. Results Patterns of functional activity showed a positive linear relationship between the activation signals and stimulation intensity in bilateral thalamus, whereas the BOLD signal of bilateral medial thalamus demonstrated that the curve was similar to the exponential function. Meanwhile, the activation in the contralateral lateral thalamus （cTh1）, but not the contralateral medial thalamus （cThm）, was prominent compared with the corresponding ipsilateral subregions, and only the lateral thalamus displayed a contralateral biased representation while the medial thalamus lacked this property. Conclusion Thalamus is one of the vital components in the pain modulation network, which can present spatial segregation activations with unique characteristics of stimulation intensityresponse in each subregion. All the results are helpful to understand the crucial role of thalamus in processing the pain information