McDougall Laura, Kiernan Dovin, Kiss Zelma H T, Suchowersky Oksana, Welsh Timothy N
Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
Faculty of Kinesiology and Physical Education, University of Toronto, 55 Harbord Street, Toronto, ON M5S 2W6, Canada; Department of Kinesiology, University of Maryland, SPH Building, College Park, MD 20742, USA.
Neurosci Lett. 2015 Sep 14;604:7-11. doi: 10.1016/j.neulet.2015.07.025. Epub 2015 Jul 26.
Surround inhibition is a neural mechanism hypothesized to facilitate goal-directed action by disinhibiting agonist muscle activity while simultaneously inhibiting antagonist and other uninvolved muscle activity. The present study was designed to investigate if abnormalities in surround inhibition are found in asymptomatic body parts (the hand) of people with focal cervical dystonia (neck). Participants with (n=7) and without (n=17) cervical dystonia completed a protocol in which they abducted their index finger while EMG was recorded from the first dorsal interosseous (agonist) and abductor digiti minimi (uninvolved) muscles. Transcranial magnetic stimulation was delivered over the primary motor cortex at intervals ranging from 0 to 950+ms after the onset of agonist muscle activity. Motor-evoked potential (MEP) amplitudes from both muscles were compared. In control participants, MEPs from the uninvolved muscle were significantly lower than agonist MEPs at intervals from 0 to 480ms. Similarly, in the hands of participants with cervical dystonia - the asymptomatic body part - MEPs from the uninvolved muscle were significantly lower than agonist MEPs from 0 to 175ms. These findings suggest that surround inhibition in people with focal dystonia may be intact in asymptomatic hands. In other words, abnormalities in surround inhibition may be restricted to the dystonic limb.
周围抑制是一种神经机制，其被假定通过解除对主动肌活动的抑制，同时抑制拮抗肌和其他未参与活动的肌肉活动，来促进目标导向动作。本研究旨在调查在局灶性颈部肌张力障碍（颈部）患者的无症状身体部位（手部）是否存在周围抑制异常。患有（n = 7）和未患有（n = 17）颈部肌张力障碍的参与者完成了一项实验方案，在该方案中，他们外展食指，同时从第一背侧骨间肌（主动肌）和小指展肌（未参与活动的肌肉）记录肌电图。在主动肌活动开始后，以0至950 +毫秒的间隔在初级运动皮层施加经颅磁刺激。比较了两块肌肉的运动诱发电位（MEP）幅度。在对照组参与者中，在0至480毫秒的间隔内，未参与活动肌肉的MEP明显低于主动肌的MEP。同样，在患有颈部肌张力障碍的参与者的手部——无症状身体部位——在0至175毫秒内，未参与活动肌肉的MEP明显低于主动肌的MEP。这些发现表明，局灶性肌张力障碍患者的周围抑制在无症状的手部可能是完整的。换句话说，周围抑制异常可能局限于肌张力障碍的肢体。
