The scientific community differs regarding involvement of the primary motor cortex (M1), the region of the cerebral cortex most nearly immediately influencing movements of the face, neck and trunk, and arm and leg, during motor imagery. Some region-of-interest analyses from fMRI experiments often reveal mild activity increases in M1 during motor imagery, while group averaged analyses from fMRI and PET do not.
Unfortunately, many of the fMRI studies showing M1 activity do not employ electrophysiological monitoring to exclude muscle contractions during actual scanning. In addition to the methodological differences, there has been some diversity among the behavioral tasks studied as motor imagery. Motor imagery is defined as the mental simulation of a motor act. This definition can include various concepts such as preparation for movement, passive observations of action, and mental operations of sensorimotor representations, either implicitly or explicitly. Motor imagery as preparation for immediate movement likely involves the motor executive brain regions including M1, since M1 plays a significant role in sensory processing for the purpose of upcoming movement generation. Implicit mental operations of sensorimotor representations, on the other hand, are considered to underlie cognitive functions such as mental rotation of body parts. It is unclear whether a motor executive area such as M1 is active not only during motor preparation but also during mental operations of sensorimotor re
Contact: Donna Krupa
American Physiological Society