Vision of the body has been reported to improve tactile acuity even when vision is not informative about the actual tactile stimulation. However, it is currently unclear whether this effect is limited to body parts such as hand, forearm or foot that can be normally viewed, or it also generalizes to body locations, such as the shoulder, that are rarely before our own eyes. In this study, subjects consecutively performed a detection threshold task and a numerosity judgment task of tactile stimuli on the shoulder. Meanwhile, they watched either a real-time video showing their shoulder or simply a fixation cross as control condition. We show that non-informative vision improves tactile numerosity judgment which might involve tactile acuity, but not tactile sensitivity. Furthermore, the improvement in tactile accuracy modulated by vision seems to be due to an enhanced ability in discriminating the number of adjacent active electrodes. These results are consistent with the view that bimodal visuotactile neurons sharp tactile receptive fields in an early somatosensory map, probably via top-down modulation of lateral inhibition.

据报道，即使视觉不能提供有关实际触觉刺激的信息，身体的视力也会提高触觉敏锐度。但是，目前尚不清楚这种效果是否仅限于可以正常查看的身体部位，例如手，前臂或脚，还是可以泛化到身体部位，例如肩膀，这些在我们自己的眼前很少见。在这项研究中，受试者连续执行肩部触觉刺激的检测阈值任务和数字判断任务。同时，他们观看了实时视频显示他们的肩膀，或者只是看了一个注视十字架作为控制状况。我们表明，非信息性视觉可以改善触觉数字判断能力，其中可能涉及触觉敏锐度，而不是触觉敏感性。此外，视觉调节触觉精度的提高似乎是由于增强了区分相邻有源电极数量的能力。这些结果与以下观点一致：双模态触觉神经元在早期体感图中可能通过自上而下的侧向抑制调制来增强触觉感受野。