L. Fadiga et al., Corticospinal excitability is specifically modulated by motor imagery: a magnetic stimulation study, NEUROPSYCHO, 37(2), 1999, pp. 147-158
Transcranial magnetic stimulation (TMS) was used to investigate whether the
excitability of the corticospinal system is selectively affected by motor
imagery. To this purpose, we performed two experiments. In the first one we
recorded motor evoked potentials from right hand and arm muscles during me
ntal simulation of flexion/extension movements of both distal and proximal
joints. In the second experiment we applied magnetic stimulation to the rig
ht and the left motor cortex of subjects while they were imagining opening
or closing their right or their left hand. Motor evoked potentials (MEPs) w
ere recorded from a hand muscle contralateral to the stimulated cortex.
The results demonstrated that the excitability pattern during motor imagery
dynamically mimics that occurring during movement execution. In addition,
while magnetic stimulation of the left motor cortex revealed increased cort
icospinal excitability when subjects imagined ipsilateral as well as contra
lateral hand movements, the stimulation of the right motor cortex revealed
a facilitatory effect induced by imagery of contralateral hand movements on
ly. In conclusion, motor imagery is a high level process, which, however, m
anifests itself in the activation of those same cortical circuits that are
normally involved in movement execution. (C) 1999 Elsevier Science Ltd. All
rights reserved.