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Abstract:
High density (128 channel) event-related potentials (ERPs)
were recorded during a mental rotation task. The specific objective
was to measure spatial distributions of ERPs elicited by the mental
rotation of hands. Sixteen, normal, right-handed subjects were
presented with line drawings of the back or palm of a left or right
hand in one of six orientations. The rotation condition involved a
right/left discrimination task in which subjects were asked to
determine as quickly as possible whether the stimulus represented a
right or left hand. In the control or non-rotation condition
subjects were required to identify the stimulus as representing
either the back or palm of a hand only. In the rotation condition
the reaction time varied systematically with the degree of
orientation away from 0 degrees of rotation (fingers upper most)
reaching a maximum at 180 degrees (fingers down). The rotation
versus control task elicited early (170ms) and late (480ms)
differences in the distribution of activation. There was a
bilateral parietal distribution and left primary motor cortex
distribution specific to the rotation task. The results support
involvement of the motor cortex in rotation tasks that may have an
implicit motor imagery component.
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