1 Department of Psychology and NeuroMI-Milan Centre for Neuroscience, University of Milano-Bicocca, Milan, Italy 2 Laboratory of Neuropsychology, IRCSS Italian Auxological Institute, Milan, Italy.
1 Department of Psychology and NeuroMI-Milan Centre for Neuroscience, University of Milano-Bicocca, Milan, Italy.
Brain. 2015 Feb;138(Pt 2):428-39. doi: 10.1093/brain/awu343. Epub 2014 Dec 5.
Limb apraxia, a deficit of planning voluntary gestures, is most frequently caused by damage to the left hemisphere, where, according to an influential neurofunctional model, gestures are planned, before being executed through the motor cortex of the hemisphere contralateral to the acting hand. We used anodal transcranial direct current stimulation delivered to the left posterior parietal cortex (PPC), the right motor cortex (M1), and a sham stimulation condition, to modulate the ability of six left-brain-damaged patients with ideomotor apraxia, and six healthy control subjects, to imitate hand gestures, and to perform skilled hand movements using the left hand. Transcranial direct current stimulation delivered to the left PPC reduced the time required to perform skilled movements, and planning, but not execution, times in imitating gestures, in both patients and controls. In patients, the amount of decrease of planning times brought about by left PPC transcranial direct current stimulation was influenced by the size of the parietal lobe damage, with a larger parietal damage being associated with a smaller improvement. Of interest from a clinical perspective, left PPC stimulation also ameliorated accuracy in imitating hand gestures in patients. Instead, transcranial direct current stimulation to the right M1 diminished execution, but not planning, times in both patients and healthy controls. In conclusion, by using a transcranial stimulation approach, we temporarily improved ideomotor apraxia in the left hand of left-brain-damaged patients, showing a role of the left PPC in planning gestures. This evidence opens up novel perspectives for the use of transcranial direct current stimulation in the rehabilitation of limb apraxia.
肢体失用症，即规划随意运动的缺陷，最常由左半球损伤引起，根据一种有影响力的神经功能模型，动作是在通过对侧大脑半球的运动皮层执行之前在左半球进行规划的。我们使用经颅直流电刺激（transcranial direct current stimulation）作用于左顶叶后皮质（posterior parietal cortex，PPC）、右运动皮层（motor cortex，M1），以及假刺激条件，来调节 6 名左脑损伤伴有意念运动性失用症的患者和 6 名健康对照者模仿手部动作以及使用左手完成熟练手部运动的能力。左顶叶皮质的经颅直流电刺激减少了执行熟练运动和模仿手势的规划时间，但对手势模仿的执行时间没有影响。在患者中，左顶叶皮质经颅直流电刺激引起的规划时间减少量受顶叶损伤大小的影响，顶叶损伤越大，改善越小。从临床角度来看，左顶叶皮质刺激还改善了患者对手势模仿的准确性。相反，右 M1 的经颅直流电刺激减少了患者和健康对照者的执行时间，但对手势模仿的规划时间没有影响。总之，通过使用经颅刺激方法，我们暂时改善了左脑损伤患者左手的意念运动性失用症，表明左顶叶皮质在规划动作中起作用。这一证据为经颅直流电刺激在肢体失用症康复中的应用开辟了新的视角。
