Movement leads to gaze-dependent spatial coding of somatosensory reach targets S Mueller, K Fiehler |
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Experimental Psychology, Justus-Liebig-University Giessen, Germany
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| Reaching towards objects requires that target and effector are coded in a common reference frame. Previous research consistently showed that remembered visual targets are represented relative to gaze [Henriques et al, 1998, The Journal of Neuroscience, 18(4), 1583-1594]. However, the reference frame used for somatosensory reach targets appears to be less clear. While some behavioral studies investigating reaches to proprioceptive targets found evidence for gaze-dependent coding, a neuroimaging study reported body-centered coding of proprioceptive stimuli. We examined the role of movement of the limb on which the targets are applied (the target effector) on spatial coding of reach targets. Subjects fixated an eccentric location while a touch was delivered to the target effector and then reached to the remembered location of the touch. We found that reach errors were unaffected by gaze when the target effector was kept stationary; however, they significantly varied with gaze when the target effector was actively moved before reaching. Introducing a gaze shift between target presentation and reaching also resulted in gaze-dependent errors which were further increased when combined with a moved target effector. In sum, our results suggest that movement of the target effector or gaze initiates gaze-dependent spatial coding of somatosensory reach targets. |
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