Abstract
On pointing or reaching movements, a target is usually in the peripheral visual field and a hand reaches toward the target after eyes moved to foveate the target. It has been suggested that a position of a remembered target for these hand movements is remapped in gaze-centered coordinates during eye movements. To investigate this remapping mechanism, we asked subjects to point a remembered target with eye-fixations. The subjects remembered a target with gazing at an initial fixation point (FP1) and moved their eyes to a second fixation point (FP2) after the target had been turned off, and pointed to the remembered target with gazing at the FP2. The following three task conditions were used: 1) the single fixation condition (SF), the FP2 appeared at the same position of the FP1 and a target was presented at the peripheral visual field; 2) the center of visual field condition (CVF), the FP2 appeared at the different position from the FP1 and a target was presented at the FP1; 3) the peripheral visual field condition (PVF), the FP2 appeared at the different position from the FP1 and a target was presented at the peripheral visual field. We assumed that the subjects calculated a sum of a FP1-target vector and a FP2-FP1 vector as a FP2-target vector (i.e., a gaze-centered remembered target position) and they had to estimate the target-FP1 and FP1-FP2 vector. The rates of miss-estimation of these vectors determined by results of the SF and CVF condition well explained results of the PVF condition. This study provides a plausible model of localization of a remembered target. [J Physiol Sci. 2006;56 Suppl:S188]
