Moving Beyond Heading. How Does the Brain Reconcile where we are Going with where we Want to Go?

Navigating successfully through the environment typically involves both detection of the current direction of travel (heading) and anticipation of changes in heading trajectory that will be required in the next few seconds. There is existing evidence that global flow patterns are encoded in visual areas MT+ and that heading may be extracted either at this level or potentially in higher areas such as VIP or CSv (e.g., Wall & Smith, 2008). In a series of studies, using fMRI, we have been exploring the neural systems engaged in integrating heading with dynamic spatial targets to enable effective steering. This talk will present evidence of increased activation in distinct regions of the superior parietal lobe (SPL) when participants are integrating future path information (upcoming bends) with current heading, when all low-level visual features are controlled for. Equivalent areas are also activated during active steering (route selection) through a slalom of obstacles as compared to steering in which participants were replayed their previous steering trials and had to mimic their virtual heading (tracking heading). Correlational analysis of fMRI data with respect to individual behavioural performance also revealed that there was increased activation of an anterior (and partially overlapping) region of the SPL in participants who exhibited smoother steering performance. These studies take the task of locomotor control beyond the simple extraction of heading from flow and elucidate the systems engaged in the spatial encoding and updating of future targets (or obstacles) with respect to current heading, which is essential for effective locomotion in any cluttered environment.