Integrative mechanisms of excitation and inhibition of the motor cortex and supplementary

点击翻译按钮获取中文摘要

We studied the integrative mechanisms of excitation and inhibition of motor cortex and supplementary sensorimotor areas in human and rat in which the following results were obtained.1. Motor function by the electrical stimulation of chronic subdural electrodes covering the motor cortex and supplementary sensorimotor areas in the patients with intractable epilepsy :The excitation and inhibition mechanisms of the motor cortex in human participate in eliciting motor evoked potentials (MEP) and silent period (SP). However, the negative motor area and supplementary sensorimotor areas have no concern with elicitation of SP.2. Conduction time between sensory and motor cortices in the patients with reflex myoclonus :The conduction time (cortical delay) between sensory and motor cortices was estimated by two methods. The one method was different time between two MEP latencies elicited by magnetic stimulation of sensory and motor cortices. The other was measurements of C reflex, SEP (N20) and ME … More P latencies from which calculated the cortical delay (cortical delay C reflex - N20 - MEP). It becomes evident from these studies that the conduction time between sensory and motor cortices is approximately 4 msec, and the pathways of C reflex (long loop reflex) are different between the patients with cortical reflex myoclonus and those with corticobasal degeneration.3. Brain function analyzing from the activities of voltage-gated sodium channels in rat brain :The activities of voltage-gated sodium channels in the rat brain were significantly increased immediately after the repetitive transcranial magnetic stimulation (rTMS, number of stimuli : 1,500/day) for 7 days consecutively (total number of stimuli : 10,500). Furthermore, those activities were significantly increased at 14th day after the rTMS, and returned to the baseline levels at 28th day after the stimulation. The number of voltage-gated soduim channels were stable after the rTMS.On the other hand, the activities of voltage-gated sodium channels at the hippocampus in the rat were not significantly increased after the rTMS.These results suggest that the changes of these activities evoked by rTM are reversible in the rat brain. The number of voltage-gated sodium channels were decreased significantly at the mesial temporal lobe in the patients with intractable temporal lobe epilepsy, although these activities were in normal levels. These results suggest that there is no excessive excitation in the hippocampus in those patients.4. No pyramidal decussation in human has been proved by the study of MEP elicited by transcranial magnetic stimulation of the motor cortex. The motor cortex undoubtedly innervates ipsilateral muscles of the upper and lower extremities in some patients. Furthermore, somatosensory pathways also ascends to the ipsilateral sensory cortex (3b area) without decussation in those subjects which has been proved by SEP study. Less