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David Field, Jac Billington, John Wann, Richard Wilkie; Parietal processing of visual information specifying “where I'm going next”. Journal of Vision 2009;9(8):1138. doi: 10.1167/9.8.1138.
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Field, Wilkie & Wann (2007) contrasted brain activation produced by travelling a curving trajectory across a ground plane with an otherwise identical stimulus that also included road edges providing advance information about changes in trajectory curvature. The addition of advance information activated a superior parietal area bordering, but distinct from, the parietal eye fields (PEF). If the novel parietal activation is due to processing of advance trajectory information then it should be driven by the distant part of the road, but not by the near road. If, on the other hand the novel parietal activation was due to lower level processing of the road edges, such as the recovery of form from motion, the parietal activation should be produced by either the distant or near road when these features are presented in isolation. Results confirmed the proposal that the superior parietal area processes advance information about changes in trajectory curvature. Relative to the ground plane only baseline condition, the near road caused an increase in the BOLD response confined to the MT+ complex, whereas the distant road activated MT+ and the parietal area. The MT+ activation produced by the near road was paralleled by a small improvement in the task of tracking instantaneous travel direction with a joystick using the flow field information. The joystick motion was open-loop and did not change the actual direction of travel. The improvement produced by adding the near road to the ground plane took the form of a reduction of tracking response lag. The parietal activation produced by the far road was accompanied by a larger reduction of the tracking response lag to zero. This suggests that the activity in the superior parietal area is specific to the processing of advance information relating to “where I'm going next” within a 1–2s prospective timeframe.
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