Gamzu E, Ahissar E
Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100, Israel.
J Neurosci. 2001 Sep 15;21(18):7416-27. doi: 10.1523/JNEUROSCI.21-18-07416.2001.
While scanning a textured surface with fingers, tactile information is encoded both spatially, by differential activation of adjacent receptors, and temporally, by changes in receptor activation during movements of the fingers across the surface. We used a tactile discrimination task to examine the dependence of human tactile perception on the availability of spatial and temporal cues. Subjects discriminated between spatial frequencies of metal gratings presented simultaneously to both hands. Tactile temporal cues were eliminated by preventing lateral hand movements; tactile spatial cues were eliminated by using gloves with an attached rubber pin. Analysis revealed separation of the subjects into two groups: "spatiotemporal" (ST) and "latent-temporal" (LT). Under normal conditions, the performance of ST subjects was significantly better than that of the LT subjects. Prevention of lateral movements impaired performance of both ST and LT subjects. However, when only temporal cues were available, the performance of ST subjects was significantly impaired, whereas that of the LT subjects either improved or did not change. Under the latter condition, LT subjects changed strategy to scanning with alternating hands, at velocities similar to the velocities normally used by ST subjects. These velocities generated temporal frequencies between 15 and 30 Hz. The LT subjects were unaware of their improved performance. Nine of ten LT subjects significantly improved their performance under normal conditions when trained to scan gratings using alternating hands and velocities similar to those used by ST subjects. We conclude that (1) temporal cues are essential for spatial-frequency discrimination, (2) human subjects vary in the tactile strategies they use for texture exploration, and (3) poor tactile performers can significantly improve by using strategies that emphasize temporal cues.
当用手指扫描有纹理的表面时，触觉信息在空间上通过相邻感受器的差异激活进行编码，在时间上通过手指在表面移动过程中感受器激活的变化进行编码。我们使用触觉辨别任务来研究人类触觉感知对空间和时间线索可用性的依赖性。受试者辨别同时呈现给双手的金属光栅的空间频率。通过防止手部横向移动来消除触觉时间线索；通过使用带有附着橡胶针的手套来消除触觉空间线索。分析显示受试者分为两组：“时空”（ST）组和“潜在时间”（LT）组。在正常情况下，ST组受试者的表现明显优于LT组受试者。防止横向移动会损害ST组和LT组受试者的表现。然而，当只有时间线索可用时，ST组受试者的表现明显受损，而LT组受试者的表现要么提高要么没有变化。在后一种情况下，LT组受试者改变策略，以与ST组受试者通常使用的速度相似的速度交替用手扫描。这些速度产生的时间频率在15到30赫兹之间。LT组受试者并未意识到自己表现的提高。当训练十名LT组受试者中的九名以与ST组受试者相同的交替用手和速度扫描光栅时，他们在正常情况下的表现显著提高。我们得出结论：（1）时间线索对于空间频率辨别至关重要；（2）人类受试者在用于纹理探索的触觉策略上存在差异；（3）触觉表现不佳者可以通过使用强调时间线索的策略显著提高表现。
