Spatial updating of hand position in younger and older adults

Navigating back to a route’s starting point can be achieved through path integration (PI) by either continuously updating self-position with respect to the starting point (continuous updating) or by computing a homing vector from a map representation of the route (configural updating). The present study investigated whether a spatial updating process analogous to PI applies to hand movements, similar to what has been observed in whole-body movements and eye movements. Younger and older adult participants followed a route of multiple locations, as indexed by audio cues, using a stylus on the surface of a tablet while their eyes were closed. At the end of the route, participants were cued to either the starting- or a mid-route location. Analysis of error and revisits suggest that participants relied more on continuous updating when only memory for the starting location was required, and relied more on configural updating when mid-route locations had to be maintained, consistent with literature on whole-body movements. Revisits were associated with more accurate performance. Older adults were less likely to revisit enroute locations, which may indicate increased reliance on continuous updating or an inability to use information extracted during configural updating to support revisits. When considered alongside literature on the contributions of the medial temporal lobe (MTL) to PI and of hippocampally-mediated representations to hand gestures, the present findings suggest that the MTL supports general spatial updating mechanisms that can be expressed across multiple effector systems.