Temporal structure of implicit motor imagery in visual hand-shape discrimination as revealed by MEG.
We investigated the spatio-temporal brain activity on the time scale of several milliseconds related to the mental rotation task requiring judgements of hand orientation, using a whole-cortex MEG (magnetoencephalography) system. Neuronal activity in the visual cortex was observed approximately 100-200 ms from stimulus onset, and that in inferior parietal lobe followed (after 200 ms). Both of these activities showed a contralateral dominance to visual stimulus hemifield. Premotor activity started later than the inferior parietal lobe activity, and these activities partially overlapped. Activity in primary motor and/or motosensory areas was observed in some subjects. The whole-cortex neuromagnetic measurements provided the time course of activity in the human brain associated with the implicit motor imagery: visual cortex-->inferior parietal lobe<-->premotor cortex. This process is considered to be the transformation process of retinotopic locations into a body-centered reference frame necessary for the mental rotation task.
Kawamichi
H
H
University of Tokyo, Japan.
Kikuchi
Y
Y
Endo
H
H
Takeda
T
T
Yoshizawa
S
S
D000328:Adult; D004193:Discrimination Learning / Q000502:physiology*; D006801:Humans; D007092:Imagination; D015225:Magnetoencephalography; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D013997:Time Factors