Lunghi Claudia, Morrone M Concetta
Department of Neuroscience, University of Florence, via San Salvi 12, 50135 Florence, Italy.
Multisens Res. 2013;26(3):291-306. doi: 10.1163/22134808-00002411.
Multisensory integration is known to occur at high neural levels, but there is also growing evidence that cross-modal signals can be integrated at the first stages of sensory processing. We investigated whether touch specifically affected vision during binocular rivalry, a particular type of visual bistability that engages neural competition in early visual cortices. We found that tactile signals interact with visual signals outside of awareness, when the visual stimulus congruent with the tactile one is perceptually suppressed during binocular rivalry and when the interaction is strictly tuned for matched visuo-tactile spatial frequencies. We also found that voluntary action does not play a leading role in mediating the effect, since the interaction was observed also when tactile stimulation was passively delivered to the finger. However, simultaneous presentation of visual and tactile stimuli is necessary to elicit the interaction, and an asynchronous priming touch stimulus is not affecting the onset of rivalry. These results point to a very early cross-modal interaction site, probably V1. By showing that spatial proximity between visual and tactile stimuli is a necessary condition for the interaction, we also suggest that the two sensory spatial maps are aligned according to retinotopic coordinates, corroborating the hypothesis of a very early interaction between visual and tactile signals during binocular rivalry.
众所周知，多感官整合发生在较高的神经层面，但越来越多的证据表明，跨模态信号可以在感觉处理的第一阶段进行整合。我们研究了在双眼竞争（一种在早期视觉皮层中引发神经竞争的特殊视觉双稳性）过程中，触觉是否会特别影响视觉。我们发现，当与触觉刺激一致的视觉刺激在双眼竞争中被感知抑制时，以及当这种相互作用严格针对匹配的视觉 - 触觉空间频率进行调谐时，触觉信号会在意识之外与视觉信号相互作用。我们还发现，自主动作在介导这种效应中并不起主导作用，因为当触觉刺激被动施加到手指上时也观察到了这种相互作用。然而，视觉和触觉刺激的同时呈现对于引发这种相互作用是必要的，并且异步启动的触觉刺激不会影响竞争的开始。这些结果指向了一个非常早期的跨模态相互作用位点，可能是初级视觉皮层（V1）。通过表明视觉和触觉刺激之间的空间接近性是这种相互作用的必要条件，我们还提出这两种感觉空间图谱是根据视网膜拓扑坐标对齐的，从而证实了在双眼竞争期间视觉和触觉信号之间非常早期相互作用的假设。
