Oscillatory α-band activity is commonly associated with spatial attention and multisensory prioritization. It has also been suggested to reflect the automatic transformation of tactile stimuli from a skin-based, somatotopic reference frame into an external one. Previous research has not convincingly separated these two possible roles of α-band activity. Previous experimental paradigms have used artificially long delays between tactile stimuli and behavioral responses to aid relating oscillatory activity to these different events. However, this strategy potentially blurs the temporal relationship of α-band activity relative to behavioral indicators of tactile-spatial transformations. Here, we assessed α-band modulation with massive univariate deconvolution, an analysis approach that disentangles brain signals overlapping in time and space. Thirty-one male and female human participants performed a delay-free, visual search task in which saccade behavior was unrestricted. A tactile cue to uncrossed or crossed hands was either informative or uninformative about visual target location. α-Band suppression following tactile stimulation was lateralized relative to the stimulated hand over central-parietal electrodes but relative to its external location over parieto-occipital electrodes. α-Band suppression reflected external touch location only after informative cues, suggesting that posterior α-band lateralization does not index automatic tactile transformation. Moreover, α-band suppression occurred at the time of, or after, the production of the saccades guided by tactile stimulation. These findings challenge the idea that α-band activity is directly involved in tactile-spatial transformation and suggest instead that it reflects delayed, supramodal processes related to attentional reorienting.

SIGNIFICANCE STATEMENT Localizing a touch in space requires integrating somatosensory information about skin location and proprioceptive or visual information about posture. The automatic remapping between skin-based tactile information to a location in external space has been proposed to rely on the modulation of oscillatory brain activity in the α-band range, across the multiple cortical areas that are involved in tactile, multisensory, and spatial processing. We report two findings that are inconsistent with this view. First, α-band activity reflected the remapped stimulus location only when touch was task relevant. Second, α-band modulation occurred too late to account for spatially directed behavioral responses and, thus, only after remapping must have taken place. These characteristics contradict the idea that α-band directly reflects automatic tactile remapping processes.

振荡性α波段活动通常与空间注意力和多感官优先级相关。还建议将触觉刺激从基于皮肤的体位参照系自动转换为外部参照系。先前的研究尚未令人信服地将α波段活性的这两种可能的作用分开。先前的实验范例在触觉刺激和行为反应之间使用了人为的长时间延迟，以帮助将振荡活动与这些不同事件相关联。但是，此策略可能会模糊α波段活动相对于触觉-空间转换的行为指标的时间关系。在这里，我们用大量的单变量反卷积评估了α波段调制，这是一种分析方法，它可以消除在时间和空间上重叠的大脑信号。31名男女参与者执行了无延迟的视觉搜索任务，其中扫视行为不受限制。未交叉或交叉的手的触觉提示对于视觉目标的位置是信息性的还是信息性的。相对于受刺激的手在顶顶中央电极上，但相对于其在顶枕顶电极上的外部位置，触觉刺激后的α波段抑制被横向化。α波段抑制仅在提供信息提示后才反映外部触摸位置，这表明后α波段侧向化不指示自动触觉转换。而且，α带抑制发生在由触觉刺激引导的扫视的产生时或之后。

重要性声明定位空间中的触摸需要整合有关皮肤位置的体感信息和有关姿势的本体感受或视觉信息。已经提出了基于皮肤的触觉信息到外部空间位置之间的自动重新映射，其依赖于涉及触觉，多感官和空间处理的多个皮质区域在α波段范围内对振荡脑活动的调制。 。我们报告了两个与该观点不一致的发现。首先，仅当触摸与任务相关时，α波段活动才反映出重新映射的刺激位置。其次，α波段调制发生得太晚，无法说明空间定向的行为响应，因此，只有在必须重新映射之后才能进行。