Cerebral Organization of Mentally Represented Prehension

Abstract:
The principle of contralateral organization was exploited to investigate contributions of the cerebral hemispheres to the mental representation of reaches in normal, right-handed, human subjects. Graphically rendered dowels were presented to either the left (LVF) or right (RVF) visual fields in a variety of different orientations, and times to determine whether an underhand or overhand grip would be preferred were measured. Although no actual reaching movements were performed, a significant advantage in grip selection time was found when judgments were based on the contralateral hand. As would be expected for actual reaching movements, judgments based on the left hand were considerably faster when visual information was directed to the LVF (right hemisphere). Judgments based on the ight hand were significantly faster when visual information was directed to the RVF (left hemisphere). Results are consistent with the position that mentally represented actions recruit mechanisms involved in movement planning. More precisely, these findings indicate that neuro-cognitive mechanisms within each cerebral hemisphere participate in mentally representing object-oriented actions of the contralateral hand.