McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
Commun Biol. 2021 May 11;4(1):559. doi: 10.1038/s42003-021-02087-0.
The brain naturally resolves the challenge of integrating auditory and visual signals produced by the same event despite different physical propagation speeds and neural processing latencies. Temporal recalibration manifests in human perception to realign incoming signals across the senses. Recent behavioral studies show it is a fast-acting phenomenon, relying on the most recent exposure to audiovisual asynchrony. Here we show that the physiological mechanism of rapid, context-dependent recalibration builds on interdependent pre-stimulus cortical rhythms in sensory brain regions. Using magnetoencephalography, we demonstrate that individual recalibration behavior is related to subject-specific properties of fast oscillations (>35 Hz) nested within a slower alpha rhythm (8-12 Hz) in auditory cortex. We also show that the asynchrony of a previously presented audiovisual stimulus pair alters the preferred coupling phase of these fast oscillations along the alpha cycle, with a resulting phase-shift amounting to the temporal recalibration observed behaviorally. These findings suggest that cross-frequency coupled oscillations contribute to forming unified percepts across senses.
大脑自然能够解决将同一事件产生的听觉和视觉信号整合在一起的挑战，尽管它们具有不同的物理传播速度和神经处理延迟。时间校准表现在人类感知中，用于在不同感觉之间重新对齐传入信号。最近的行为研究表明，这是一种快速作用的现象，依赖于对视听失谐的最新暴露。在这里，我们表明，快速、上下文相关的重新校准的生理机制建立在感觉大脑区域中相互依赖的预刺激皮质节律之上。使用脑磁图，我们证明个体的重新校准行为与听觉皮层中嵌套的较慢 alpha 节律（8-12 Hz）内的快振荡（>35 Hz）的特定于个体的特性有关。我们还表明，先前呈现的视听刺激对改变了这些快振荡沿 alpha 周期的首选耦合相位，从而产生与行为上观察到的时间重新校准相对应的相移量。这些发现表明，跨频耦合振荡有助于形成跨感觉的统一感知。
