Department of Neurology, University of Lübeck, Germany.
Brain Cogn. 2011 Oct;77(1):138-50. doi: 10.1016/j.bandc.2011.05.004. Epub 2011 Jun 23.
In patients with the callosal type of anarchic-hand syndrome, the left hand often does not act as intended and counteracts the right hand. Reports are scarce about the underlying neurophysiological mechanisms. We report the case G.H. who developed the syndrome after infarction of the left arteria pericallosa. It has been suggested that the syndrome arises out of lacking inhibition from the dominant left hemisphere on the right hemisphere. Yet, in tests of spatial intelligence G.H. performed much better with his "anarchic" left hand than with his dominant right hand, similar to observations commonly reported in split-brain patients. Left-right manual choice responses and event-related EEG potentials to laterally presented stimuli were measured. Asymmetries were evident in G.H.'s behavior and EEG potentials, different from age-matched healthy participants (n=11). His right-hand responses were fast and unaffected by incompatibility with stimulus location, whereas his left-hand responses were variable and accompanied by a large negative central-midline EEG potential, probably reflecting efforts in initiating the response. G.H.'s visual N1 component peaked earlier and was larger at the right than the left side of the scalp, and the P3 component was distinctly reduced at the right side. Both features occurred independent of side of stimulus presentation and side of responding hand. The effort indicated by the midline negativity and the asymmetrically reduced P3 might directly reflect G.H.'s lack of control on his right hemisphere's processing. The faster visual processing of the right hemisphere suggested by the N1 asymmetry might contribute to "anarchic" processing, making the right hemisphere process stimuli before control impulses exert their effect. These neurophysiological results tend to support the split-brain account which assumes that the syndrome arises by the lack of communication between hemispheres that act according to their respective competences.
在胼胝体性运动不能性失用症患者中，左手常常不能按照预期的那样运动，反而与右手对抗。关于其潜在的神经生理机制的报告很少。我们报告了 G.H. 的病例，他在左胼胝体动脉梗塞后出现了这种综合征。有人认为，这种综合征是由于左半球对右半球缺乏抑制作用引起的。然而，在空间智能测试中，G.H. 用他的“失控”左手的表现明显优于惯用右手，这与裂脑患者的常见观察结果相似。我们测量了他左右手动选择反应和与侧向呈现刺激相关的事件相关 EEG 电位。G.H. 的行为和 EEG 电位存在明显的左右不对称，与年龄匹配的健康参与者（n=11）不同。他的右手反应迅速，不受与刺激位置不兼容的影响，而他的左手反应则不稳定，伴随着一个大的负中央中线 EEG 电位，可能反映了发起反应的努力。G.H. 的视觉 N1 成分在头皮右侧比左侧更早且更大，而 P3 成分在右侧明显减小。这两个特征都与刺激呈现侧和反应手侧无关。中线负电和明显减小的 P3 所表示的努力可能直接反映了 G.H. 对其右半球处理的缺乏控制。N1 不对称所暗示的右半球更快的视觉处理可能有助于“失控”处理，使右半球在控制冲动发挥作用之前处理刺激。这些神经生理学结果倾向于支持裂脑假说，该假说假设这种综合征是由于两个半球之间缺乏根据各自的能力进行交流引起的。
