Schrafl-Altermatt Miriam, Dietz Volker
Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland.
Neuroreport. 2014 Dec 17;25(18):1429-32. doi: 10.1097/WNR.0000000000000285.
Task-specific neural coupling during cooperative hand movements has been described in healthy volunteers, manifested by bilateral reflex electromyographic responses in forearm muscles following unilateral ulnar nerve stimulation and by task-specific activation of secondary somatosensory cortical areas (S2) in functional MRI. The aim of this study was to investigate the role of sensory input to the ipsilateral and contralateral cortex during a cooperative task. Somatosensory evoked potentials from the ulnar nerve were recorded over the ipsilateral and contralateral cortex during resting and during cooperative and noncooperative hand movements. Ipsilateral potentials with smaller amplitude were present under all conditions in almost all participants. In relation to the resting condition, the amplitudes of both the ipsilateral and the contralateral potential were reduced during the cooperative and the noncooperative tasks. Nevertheless, the reduction in amplitude was similar for the ipsilateral and the contralateral potentials in the noncooperative task, but less on the ipsilateral compared with the contralateral side during the cooperative task. The ratio of ipsilateral/contralateral somatosensory evoked potential amplitude was thus significantly larger during the cooperative task compared with the control task and the resting condition. This indicates a functional role of ipsilateral pathways connecting the cervical spinal cord with the cortex during the cooperative task. These observations favor the idea of a task-specific mediation of sensory input from both hands to the ipsilateral and contralateral hemispheres as the basis of neuronal coupling.
健康志愿者在协同手部运动过程中存在特定任务的神经耦合现象，表现为单侧尺神经刺激后前臂肌肉出现双侧反射性肌电图反应，以及功能磁共振成像中次级体感皮层区域（S2）的特定任务激活。本研究的目的是调查在协同任务期间感觉输入对同侧和对侧皮层的作用。在静息状态、协同和非协同手部运动期间，记录同侧和对侧皮层上来自尺神经的体感诱发电位。几乎所有参与者在所有条件下均存在幅度较小的同侧电位。与静息状态相比，协同任务和非协同任务期间同侧和对侧电位的幅度均降低。然而，在非协同任务中，同侧和对侧电位的幅度降低相似，但在协同任务期间，同侧电位幅度的降低幅度比对侧小。因此，与对照任务和静息状态相比，协同任务期间同侧/对侧体感诱发电位幅度的比值显著更大。这表明在协同任务期间，同侧通路在连接颈脊髓与皮层方面具有功能性作用。这些观察结果支持这样一种观点，即双手的感觉输入通过特定任务介导至同侧和对侧半球，这是神经元耦合的基础。
