以功能性磁振造影探討大腦與上臂週邊神經系統功能性連結之初步研究

Abstract

人體的運動行為是由中樞與週邊神經系統相互調控的。過去研究發現藉由量測主動或病理性的肌肉收縮相關訊號，證實大腦皮質與上臂週邊神經系統具有同調性。先前在行為認知實驗也指出大腦特定的運動皮質區會調控不同的肌肉協同作用，且會參與不同的大腦網路。然而，目前對於大腦皮質與週邊神經系統間功能性連結之研究相對較少。因此，在本研究中，我們將探討大腦皮質與上臂週邊神經系統功能性網路連結之關係。 本研究共收錄三十七位健康受試者，藉由三個不同線圈之搭配組合，同步收取大腦及上肢在任務態以及靜息態的功能磁共振造影的迴訊平面造影信號。在任務態的腦功能磁共振造影的實驗中，受試者需執行或想像手部動作；而在靜息態的腦功能磁共振造影的實驗中，受試者需張眼並且不做任何系統性思考的行為。實驗數據以一般線性模型、種子相關分析、區域配對相關係數與獨立成分分析做功能性影像分析。 在任務態功能性磁振造影發現，在中央前腦回、輔助運動區有顯著性的活化。而在靜息態功能性磁振造影發現，上臂週邊神經系統與左背外側前額葉皮層，中央溝前側腦回，左頂下葉腦回，前扣帶迴皮質，以及小腦有顯著的功能性連結，並會參與大腦功能性網路之變化，如：運動、感覺運動、執行控制網路、預設模式網路、視丘、小腦、體感覺網路。而在顳葉迴，梭狀回，腦島，海馬旁回，扣帶皮層，杏仁核，以及小腦和上臂週邊神經系統有顯著的區域相關係數 。 本研究在傳統認知功能性磁振影像基礎上，採用不同之實驗方式，同步收取大腦及上肢的功能磁共振造影迴訊平面造影信號。在本研究之結果中，上臂週邊神經系統與大腦之間有密切的功能性連結，上臂週邊神經系統除了與大腦動作控制網絡有高度之功能性連結，並且參與調控大腦認知相關網路之功能。本研究初步開啟了以影像方法同步探究中樞與週邊神經系統之連結，未來期望可應用於神經系統間之相互整合研究，以提供臨床輔助診斷之參考依據。

The human movement is a behavior from the cooperation between central and peripheral nervous system. Previous studies confirmed the coherence between the cerebral cortex and the peripheral nervous system of upper limb by measuring the muscle signals form active or pathological muscle contraction, terming corticomuscular coherence. In addition, the specific motor cortical area would modulate the different muscle synergies, and be involved in distinct brain functional network. However, few studies focused on the relationship between the brain functional networks and peripheral nervous system. This study aimed to explore the functional coupling between the central nervous system and the peripheral nervous system of upper limb. Thirty-seven healthy subjects participated in the functional magnetic resonance imaging (fMRI) experiments. We established the imaging platform to collect the echo planar imaging (EPI) signals under the experimental design of task-based and task-free fMRI from human brain and upper limb simultaneously. All data were acquired using three coils: one 20-channels head coil, one 32-channels spine coil, and one 18-channels flexible surface coil. In the task-based sessions, the participants were instructed to execute or image hand movement; in the task-free fMRI scanning, participants were asked to open their eyes and do not think systematically. Generalized linear modeling, seed-based functional connectivity, regional pairwise correlation coefficient (RPCC) and independent component analysis were used for the functional data analyzing. Our result demonstrated that the peripheral nervous system of upper limb and the motor-related cerebral areas, including of precentral gyrus and supplementary motor area, had significant activation in the task-based fMRI. Seeding at the peripheral activation during motor tasks, the functional connectivity was identified in several brain regions, included the left dorsolateral prefrontal cortex, precentral gyrus, left inferior parietal gyrus, anterior cingulate cortex, and cerebellar lobules. The peripheral nervous system of upper limb showed that the most-linked hub-regions in middle temporal gyrus, fusiform gyrus, insula, parahippocampal gyrus, cingulate cortex, amygdala, cerebellar lobule Crus I, and cerebellar lobule VII. In the result analyzed by ICA, the peripheral nervous system of upper limb would involve in the brain functional network, including motor, sensorimotor, executive control network, default mode network, thalamus, cerebellum, and somatosensory network. We established a novel imaging-platform to collect the functional images from human brain and upper limb simultaneously. This study disclosed the functional coupling between the peripheral nervous system of upper limb and the brain cortex and demonstrated that peripheral nervous system also involved in the regulation of brain cognitive function and related network changes. We expect that it could be applied furthering investigation of central-peripheral communication and could be used in the clinical diagnosis.