title: Facilitation and reciprocal inhibition by imagining thumb abduction.
abstract: It is well known that motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) of the motor cortex are facilitated by voluntary muscle contraction. We evaluated the effects of imagination of movements on MEP latencies of agonist and antagonist muscles in the hand using TMS. Twenty-two healthy volunteers were studied. TMS delivered at rest and while imagining tonic abduction of the right thumb. MEPs were recorded in response to magnetic stimulation over the scalp and cervical spine (C7-T1), and central motor conduction times (CMCT) were calculated. MEPs were recorded from right abductor pollicis brevis muscle (APB) and adductor pollicis muscle (AP) simultaneously. Imagination of abduction resulted in a shortened latency of MEPs in the APB muscle, and a prolonged latency in the AP muscle. But the imagination caused no significant change in the latency of MEPs elicited by stimulation over the cervical spine. The changes of the CMCT may account for these latency changes with imagination of movement. These findings indicate that imagination of thumb abduction facilitates motoneurons of agonist muscle and has an inhibitory effect on those of antagonist muscle (reciprocal inhibition).
authors.affiliation: Department of Neurology, Sanbon Hospital, College of Medicine, Wonkwang University, 1142, Sanbon-dong, Gunpo-si, Gyungki-do, 435 040, South Korea. vcyang@wonkwang.ac.kr
authors.forename: Hyun Duk
authors.initials: HD
authors.lastname: Yang
authors.forename: Yang Ki
authors.initials: YK
authors.lastname: Minn
authors.forename: Il Hong
authors.initials: IH
authors.lastname: Son
authors.forename: Seung Han
authors.initials: SH
authors.lastname: Suk
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D007092:Imagination / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D011859:Radiography; D013933:Thumb / Q000000981:diagnostic imaging* / Q000502:physiology; D050781:Transcranial Magnetic Stimulation