Laboratory of Brain Imaging, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura Street, 02-093, Warsaw, Poland; Institute of Psychology, Jagiellonian University, 6 Ingardena Street, 30-060, Krakow, Poland.
Laboratory of Brain Imaging, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura Street, 02-093, Warsaw, Poland.
Neuroimage. 2019 Nov 15;202:116084. doi: 10.1016/j.neuroimage.2019.116084. Epub 2019 Aug 7.
Perception via different sensory modalities was traditionally believed to be supported by largely separate brain systems. However, a growing number of studies demonstrate that the visual cortices of typical, sighted adults are involved in tactile and auditory perceptual processing. Here, we investigated the spatiotemporal dynamics of the visual cortex's involvement in a complex tactile task: Braille letter recognition. Sighted subjects underwent Braille training and then participated in a transcranial magnetic stimulation (TMS) study in which they tactually identified single Braille letters. During this task, TMS was applied to their left early visual cortex, visual word form area (VWFA), and left early somatosensory cortex at five time windows from 20 to 520 ms following the Braille letter presentation's onset. The subjects' response accuracy decreased when TMS was applied to the early visual cortex at the 120-220 ms time window and when TMS was applied to the VWFA at the 320-420 ms time window. Stimulation of the early somatosensory cortex did not have a time-specific effect on the accuracy of the subjects' Braille letter recognition, but rather caused a general slowdown during this task. Our results indicate that the involvement of sighted people's visual cortices in tactile perception respects the canonical visual hierarchy-the early tactile processing stages involve the early visual cortex, whereas more advanced tactile computations involve high-level visual areas. Our findings are compatible with the metamodal account of brain organization and suggest that the whole visual cortex may potentially support spatial perception in a task-specific, sensory-independent manner.
传统上，人们认为不同感觉模式的感知是由很大程度上相互独立的大脑系统支持的。然而，越来越多的研究表明，典型的、有视力的成年人的视觉皮层参与了触觉和听觉感知处理。在这里，我们研究了视觉皮层参与复杂触觉任务（盲文字母识别）的时空动力学。视力正常的受试者接受了盲文训练，然后参加了一项经颅磁刺激 (TMS) 研究，在该研究中，他们通过触觉识别单个盲文字母。在这项任务中，TMS 在盲文字母呈现开始后 20 到 520 毫秒的五个时间窗口中施加于他们的左早期视觉皮层、视觉词形区 (VWFA) 和左早期体感皮层。当 TMS 在 120-220 毫秒的时间窗口施加于早期视觉皮层时，当 TMS 在 320-420 毫秒的时间窗口施加于 VWFA 时，受试者的反应准确性会下降。刺激早期体感皮层不会对受试者的盲文字母识别准确性产生特定时间的影响，而是在这项任务中导致整体减速。我们的结果表明，视力正常者的视觉皮层参与触觉感知符合规范的视觉层次结构——早期触觉处理阶段涉及早期视觉皮层，而更高级的触觉计算涉及高级视觉区域。我们的发现与大脑组织的多模态理论一致，并表明整个视觉皮层可能以任务特异性、感觉独立性的方式潜在地支持空间感知。
