McMaster Integrative Neuroscience Discovery and Study, McMaster University, Hamilton, Ontario, Canada.
PLoS One. 2011;6(9):e25277. doi: 10.1371/journal.pone.0025277. Epub 2011 Sep 23.
An important unresolved question in sensory neuroscience is whether, and if so with what time course, tactile perception is enhanced by visual deprivation. In three experiments involving 158 normally sighted human participants, we assessed whether tactile spatial acuity improves with short-term visual deprivation over periods ranging from under 10 to over 110 minutes. We used an automated, precisely controlled two-interval forced-choice grating orientation task to assess each participant's ability to discern the orientation of square-wave gratings pressed against the stationary index finger pad of the dominant hand. A two-down one-up staircase (Experiment 1) or a Bayesian adaptive procedure (Experiments 2 and 3) was used to determine the groove width of the grating whose orientation each participant could reliably discriminate. The experiments consistently showed that tactile grating orientation discrimination does not improve with short-term visual deprivation. In fact, we found that tactile performance degraded slightly but significantly upon a brief period of visual deprivation (Experiment 1) and did not improve over periods of up to 110 minutes of deprivation (Experiments 2 and 3). The results additionally showed that grating orientation discrimination tends to improve upon repeated testing, and confirmed that women significantly outperform men on the grating orientation task. We conclude that, contrary to two recent reports but consistent with an earlier literature, passive tactile spatial acuity is not enhanced by short-term visual deprivation. Our findings have important theoretical and practical implications. On the theoretical side, the findings set limits on the time course over which neural mechanisms such as crossmodal plasticity may operate to drive sensory changes; on the practical side, the findings suggest that researchers who compare tactile acuity of blind and sighted participants should not blindfold the sighted participants.
感觉神经科学中一个未解决的重要问题是，触觉感知是否会因视觉剥夺而增强，如果会，其时间进程如何。在涉及 158 名正常视力的人类参与者的三项实验中，我们评估了在 10 分钟以下到 110 分钟以上的短时间视觉剥夺期间，触觉空间敏锐度是否会提高。我们使用自动化、精确控制的两间隔强制选择光栅方向任务来评估每个参与者辨别正方形波光栅方向的能力，这些光栅被按压在优势手的静止食指垫上。使用两降一升阶梯（实验 1）或贝叶斯自适应程序（实验 2 和 3）来确定每个参与者能够可靠区分的光栅的槽宽。实验一致表明，短期视觉剥夺不会提高触觉光栅方向辨别能力。事实上，我们发现，短暂的视觉剥夺会导致触觉性能略有但显著下降（实验 1），而长达 110 分钟的剥夺期内并没有改善（实验 2 和 3）。结果还表明，光栅方向辨别能力随着重复测试而提高，并证实女性在光栅方向任务上明显优于男性。我们得出的结论是，与最近的两项报告相反，但与早期文献一致，短期视觉剥夺不会增强被动触觉空间敏锐度。我们的研究结果具有重要的理论和实践意义。在理论方面，这些发现限制了跨模态可塑性等神经机制可能发挥作用以驱动感觉变化的时间进程；在实践方面，这些发现表明，比较盲人和视力正常参与者的触觉敏锐度的研究人员不应遮住视力正常参与者的眼睛。
