Abstract& Far (extrapersonal) and near (peripersonal) spaces are behaviorally defined as the space outside the hand-reaching distance and the space within the hand-reaching distance. Animal and human studies have confirmed this distinction, showing that space is not homogeneously represented in the brain. In this paper we demonstrate that the coding of space as ''far'' and ''near'' is not only determined by the hand-reaching distance, but it is also dependent on how the brain represents the extension of the body space. We will show that when the cerebral representation of body space is extended to include objects or tools used by the subject, space previously mapped as far can be remapped as near. Patient P.P., after a right hemisphere stroke, showed a dissociation between near and far spaces in the manifestation of neglect. Indeed, in a line bisection task, neglect was apparent in near space, but not in far space when bisection in the far space was performed with a projection lightpen. However, when in the far space bisection was performed with a stick, used by the patient to reach the line, neglect appeared and was as severe as neglect in the near space. An artificial extension of the patient's body (the stick) caused a remapping of far space as near space. &
In everyday life, the successful monitoring of behavior requires continuous updating of the effectiveness of motor acts; one crucial step is becoming aware of the movements one is performing. We studied the anatomical distribution of lesions in right-brain-damaged hemiplegic patients, who obstinately denied their motor impairment, claiming that they could move their paralyzed limbs. Denial was associated with lesions in areas related to the programming of motor acts, particularly Brodmann's premotor areas 6 and 44, motor area 4, and the somatosensory cortex. This association suggests that monitoring systems may be implemented within the same cortical network that is responsible for the primary function that has to be monitored.
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