Daskalakis Zafiris J, Paradiso Guillermo O, Christensen Bruce K, Fitzgerald Paul B, Gunraj Carolyn, Chen Robert
Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
J Physiol. 2004 Jun 1;557(Pt 2):689-700. doi: 10.1113/jphysiol.2003.059808. Epub 2004 Mar 26.
Animal studies have shown that cerebellar projections influence both excitatory and inhibitory neurones in the motor cortex but this connectivity has yet to be demonstrated in human subjects. In human subjects, magnetic or electrical stimulation of the cerebellum 5-7 ms before transcranial magnetic stimulation (TMS) of the motor cortex decreases the TMS-induced motor-evoked potential (MEP), indicating a cerebellar inhibition of the motor cortex (CBI). TMS also reveals inhibitory and excitatory circuits of the motor cortex, including a short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI) and intracortical facilitation (ICF). This study used magnetic cerebellar stimulation to investigate connections between the cerebellum and these cortical circuits. Three experiments were performed on 11 subjects. The first experiment showed that with increasing test stimulus intensities, LICI, CBI and ICF decreased, while SICI increased. The second experiment showed that the presence of CBI reduced SICI and increased ICF. The third experiment showed that the interaction between CBI and LICI reduced CBI. Collectively, these findings suggest that cerebellar stimulation results in changes to both inhibitory and excitatory neurones in the human motor cortex.
动物研究表明，小脑投射会影响运动皮层中的兴奋性和抑制性神经元，但这种连接性在人类受试者中尚未得到证实。在人类受试者中，在对运动皮层进行经颅磁刺激（TMS）前5 - 7毫秒对小脑进行磁刺激或电刺激，会降低TMS诱发的运动诱发电位（MEP），这表明小脑对运动皮层有抑制作用（CBI）。TMS还揭示了运动皮层的抑制性和兴奋性回路，包括短间隔皮质内抑制（SICI）、长间隔皮质内抑制（LICI）和皮质内易化（ICF）。本研究使用磁刺激小脑来研究小脑与这些皮质回路之间的联系。对11名受试者进行了三个实验。第一个实验表明，随着测试刺激强度的增加，LICI、CBI和ICF降低，而SICI增加。第二个实验表明，CBI的存在会降低SICI并增加ICF。第三个实验表明，CBI和LICI之间的相互作用会降低CBI。总体而言，这些发现表明，小脑刺激会导致人类运动皮层中抑制性和兴奋性神经元发生变化。
