Division of Neuroscience, Department of Neurology, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Exp Brain Res. 2012 Apr;218(1):21-6. doi: 10.1007/s00221-011-2997-0. Epub 2012 Jan 11.
In mild cognitive impairment (MCI), the corpus callosum is known to be affected structurally. We evaluated callosal function by interhemispheric inhibition (IHI) using transcranial magnetic stimulation (TMS) in MCI patients. We investigated 12 amnestic MCI patients and 16 healthy age-matched control subjects. The IHI was studied with a paired-pulse TMS technique. The conditioning TMS was given over the right primary motor cortex (M1) and the test TMS over the left M1. Motor evoked potentials were recorded from the relaxed first dorsal interosseous muscle. We also studied other motor cortical circuit functions; short-latency afferent inhibition (SAI), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). Both the amount of IHI and SAI were significantly reduced in MCI patients as compared with control subjects, whereas SICI or ICF did not differ between them. The degree of IHI significantly correlated with neither the mini-mental state examination score nor the degree of SAI. Our results suggest that transcallosal connection between bilateral M1 is primarily involved in MCI, regardless of SAI dysfunction.
在轻度认知障碍（MCI）中，已知胼胝体在结构上受到影响。我们通过使用经颅磁刺激（TMS）评估 MCI 患者的胼胝体功能。我们研究了 12 名遗忘型 MCI 患者和 16 名年龄匹配的健康对照组。使用成对脉冲 TMS 技术研究了 IHI。刺激 TMS 施加于右侧初级运动皮层（M1），测试 TMS 施加于左侧 M1。从放松的第一背间骨间肌记录运动诱发电位。我们还研究了其他运动皮质回路功能；短潜伏期传入抑制（SAI），短间隔皮质内抑制（SICI）和皮质内易化（ICF）。与对照组相比，MCI 患者的 IHI 和 SAI 量均明显降低，而 SICI 或 ICF 则无差异。IHI 的程度与简易精神状态检查评分或 SAI 的程度均无显著相关性。我们的结果表明，双侧 M1 之间的胼胝体连接主要与 MCI 有关，而与 SAI 功能障碍无关。
