Are action and perception in near and far space additive or interactive factors?
Functional imaging has revealed differential neural mechanisms underlying action directed toward near or far space. Because some neuropsychological studies of patients with visuospatial neglect failed to show near/far dissociations with perceptual tasks, we investigated whether action and perception elicit distinct cerebral representations in near and far space. We measured regional cerebral blood flow with positron emission tomography in normal volunteers who performed manual line bisection (action) and made line bisection judgments (perception). Stimuli were presented in near space or far space. Far space presentation enhanced activations in occipital cortex extending into the medial occipitotemporal cortex bilaterally, while near space presentation enhanced left occipital-parietal, parietal, and premotor cortex activity. Manual bisection activated the extrastriate, superior parietal, and premotor cortex bilaterally, while bisection judgments activated the right inferior parietal cortex, anterior cingulate, right dorsolateral prefrontal cortex, and extrastriate and superior temporal cortex bilaterally. The neural mechanisms responsible for the two tasks (perceptual/motor) were not differentially modulated by space of presentation.
Institute of Medicine, Forschungszentrum Jülich, 52425 Jülich, Germany.
Peter H
PH
Weiss
John C
JC
Marshall
Karl
K
Zilles
Gereon R
GR
Fink
D000328:Adult; D001519:Behavior / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D005133:Eye Movements / Q000502:physiology; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009778:Occipital Lobe / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D013028:Space Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology; D014055:Tomography, Emission-Computed