Koch Giacomo, Ribolsi Michele, Mori Francesco, Sacchetti Lucia, Codecà Claudia, Rubino Ivo Alex, Siracusano Alberto, Bernardi Giorgio, Centonze Diego
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Biol Psychiatry. 2008 Nov 1;64(9):815-9. doi: 10.1016/j.biopsych.2008.05.026. Epub 2008 Jul 16.
Recent advances have highlighted the hypothesis of schizophrenia as a disorder causing defective connectivity among distinct cortical regions. Neurophysiological evidence supporting this hypothesis, however, is still lacking.
In the present study, we used a novel twin-coil transcranial magnetic stimulation (tcTMS) approach to investigate ipsilateral parieto-motor connectivity in 20 schizophrenic patients (14 medicated, 6 unmedicated) and in 15 healthy age-matched volunteers.
In healthy subjects, a conditioning TMS pulse applied over the ipsilateral posterior parietal cortex (PPC) at 90% of resting motor threshold (RMT) intensity was able to increase the excitability of the hand area of the right primary motor cortex, with peaks at interstimulus intervals (ISIs) of 4 and 15 msec. This paradigm of stimulation failed to reveal any facilitatory parieto-motor interaction in medicated and unmedicated schizophrenic patients. The between-group difference in paired-pulse facilitation was not ISI-specific. In following analyses, we found that the effects across ISIs induced by PPC conditioning at 90% RMT correlated with the Global Assessment Functioning score and with the negative subscale of the Positive and Negative Syndrome Scale, showing that patients with a better global functioning and lower negative symptoms had less impaired connectivity. Moreover the same parameter correlated with illness duration.
Parieto-motor connectivity is impaired in schizophrenia. Cortico-cortical disconnection might be a core feature of schizophrenia.
近期的研究进展突出了精神分裂症是一种导致不同皮质区域间连接缺陷的疾病这一假说。然而，支持该假说的神经生理学证据仍然缺乏。
在本研究中，我们使用了一种新型双线圈经颅磁刺激（tcTMS）方法，来研究20例精神分裂症患者（14例正在服药，6例未服药）和15名年龄匹配的健康志愿者的同侧顶叶 - 运动连接性。
在健康受试者中，以静息运动阈值（RMT）强度的90%在同侧后顶叶皮质（PPC）施加条件性TMS脉冲，能够增加右侧初级运动皮质手部区域的兴奋性，在刺激间隔（ISI）为4毫秒和15毫秒时达到峰值。这种刺激模式未能在服药和未服药的精神分裂症患者中揭示任何促进性的顶叶 - 运动相互作用。配对脉冲易化的组间差异并非ISI特异性的。在后续分析中，我们发现，在90%RMT时由PPC条件刺激诱导的跨ISI效应与总体评估功能评分以及阳性和阴性症状量表的阴性分量表相关，表明总体功能较好且阴性症状较轻的患者连接性受损程度较小。此外，相同参数与病程相关。
精神分裂症患者存在顶叶 - 运动连接受损。皮质 - 皮质断开可能是精神分裂症的核心特征。
