Brown Liana E, Marlin Matthew C, Morrow Sarah
Department of Psychology, Trent University, Peterborough, Ontario, Canada
Department of Psychology, Trent University, Peterborough, Ontario, Canada.
J Neurophysiol. 2015 Jan 15;113(2):409-19. doi: 10.1152/jn.00005.2014. Epub 2014 Oct 22.
Performance is often improved when targets are presented in space near the hands rather than far from the hands. Performance in hand-near space may be improved because participants can use proprioception from the nearby limb and hand to provide a narrower and more resolute frame of reference. An equally compelling alternative is that targets appearing near the hand fall within the receptive fields of visual-tactile bimodal cells, recruiting them to assist in the visual representation of targets that appear near but not far from the hand. We distinguished between these two alternatives by capitalizing on research showing that vision and proprioception have differential effects on the precision of target representation (van Beers RJ, Sittig AC, Denier van der Gon JJ. Exp Brain Res 122: 367-377, 1998). Participants performed an in-to-center reaching task to an array of central target locations with their right hand, while their left hand rested near (beneath) or far from the target array. Reaching end-point accuracy, variability, time, and speed were assessed. We predicted that if proprioception contributes to the representation of hand-near targets, then error variability in depth will be smaller in the hand-near condition than in the hand-far condition. By contrast, if vision contributes to the representation of hand-near targets, then error variability along the lateral dimension will be smaller in the hand-near than in the hand-far condition. Our results showed that the placement of the hand near the targets reduced end-point error variability along the lateral dimension only. The results suggest that hand-near targets are represented with greater visual resolution than far targets.
当目标出现在手部附近的空间而不是远离手部的空间时，表现通常会得到改善。手部附近空间的表现可能会得到改善，因为参与者可以利用来自附近肢体和手部的本体感觉来提供一个更窄且更坚定的参照框架。另一个同样有说服力的观点是，出现在手部附近的目标落入了视觉-触觉双峰细胞的感受野内，从而促使这些细胞协助对手部附近但不远处出现的目标进行视觉表征。我们利用一项研究来区分这两种观点，该研究表明视觉和本体感觉对目标表征的精度有不同影响（van Beers RJ, Sittig AC, Denier van der Gon JJ. Exp Brain Res 122: 367 - 377, 1998）。参与者用右手执行一项向一系列中央目标位置进行向心伸手任务，同时左手放在目标阵列附近（下方）或远离目标阵列。评估伸手终点的准确性、变异性、时间和速度。我们预测，如果本体感觉有助于手部附近目标的表征，那么在手部附近条件下深度方向的误差变异性将比手部远离条件下更小。相比之下，如果视觉有助于手部附近目标的表征，那么在手部附近条件下横向维度的误差变异性将比手部远离条件下更小。我们的结果表明，将手放在目标附近仅降低了横向维度的终点误差变异性。结果表明，手部附近的目标比远处的目标具有更高的视觉分辨率。
