An fMRI study of parietal cortex involvement in the visual guidance of locomotion.
Locomoting through the environment typically involves anticipating impending changes in heading trajectory in addition to maintaining the current direction of travel. We explored the neural systems involved in the "far road" and "near road" mechanisms proposed by Land and Horwood (1995) using simulated forward or backward travel where participants were required to gauge their current direction of travel (rather than directly control it). During forward egomotion, the distant road edges provided future path information, which participants used to improve their heading judgments. During backward egomotion, the road edges did not enhance performance because they no longer provided prospective information. This behavioral dissociation was reflected at the neural level, where only simulated forward travel increased activation in a region of the superior parietal lobe and the medial intraparietal sulcus. Providing only near road information during a forward heading judgment task resulted in activation in the motion complex. We propose a complementary role for the posterior parietal cortex and motion complex in detecting future path information and maintaining current lane positioning, respectively.
Billington
Jac
J
Department of Psychology, University of London, Egham, Surrey, UK. Jaclyn.billington@rhul.ac.uk
Field
David T
DT
Wilkie
Richard M
RM
Wann
John P
JP
D000328:Adult; D001931:Brain Mapping; D003463:Cues; D004215:Distance Perception / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007699:Kinesthesis / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology; D057849:Optic Flow / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012438:Saccades / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult