Center for Mind/Brain Sciences, University of Trento, Trento, 38122, Italy.
Centre for Human Brain Health and School of Psychology, University of Birmingham, Birmingham, B15 2TT, United Kingdom.
J Neurosci. 2022 Oct 12;42(41):7824-7832. doi: 10.1523/JNEUROSCI.0509-22.2022. Epub 2022 Sep 13.
The perception of dynamic visual stimuli relies on two apparently conflicting perceptual mechanisms: rapid visual input must sometimes be integrated into unitary percepts but at other times must be segregated or parsed into separate objects or events. Though they have opposite effects on our perceptual experience, the deployment of spatial attention benefits both operations. Little is known about the neural mechanisms underlying this impact of spatial attention on temporal perception. Here, we record magnetoencephalography (MEG) in male and female humans to demonstrate that the deployment of spatial attention for the purpose of segregating or integrating visual stimuli impacts prestimulus oscillatory activity in retinotopic visual brain areas where the attended location is represented. Alpha band oscillations contralateral to an attended location are therefore faster than ipsilateral oscillations when stimuli appearing at this location will need to be segregated, but slower in expectation of the need for integration, consistent with the idea that α frequency is linked to perceptual sampling rate. These results demonstrate a novel interaction between temporal visual processing and the allocation of attention in space. Our environment is dynamic and visual input therefore varies over time. To make sense of continuously changing information, our visual system balances two complementary processes: temporal segregation in order to identify changes, and temporal integration to identify consistencies in time. When we know that a circumstance requires use of one or the other of these operations, we are able to prepare for this, and this preparation can be tracked in oscillatory brain activity. Here, we show how this preparation for temporal processing can be focused spatially. When we expect to integrate or segregate visual stimuli that will appear at a specific location, oscillatory brain activity changes in visual areas responsible for the representation of that location. In this way, spatial and temporal mechanisms interact to support adaptive, efficient perception.
快速的视觉输入有时必须整合为单一的感知，但有时必须分割或解析为单独的物体或事件。尽管它们对我们的感知体验有相反的影响，但空间注意力的运用有利于这两种操作。关于空间注意力对时间感知的影响的神经机制知之甚少。在这里，我们通过记录男性和女性的脑磁图（MEG）来证明，为了分割或整合视觉刺激而部署空间注意力会影响到代表注视位置的视网膜视觉脑区的前刺激振荡活动。当需要在该位置分离刺激时，与注视位置相对侧的α 波段振荡比同侧振荡快，但在需要整合的情况下则较慢，这与α 频率与感知采样率相关的观点一致。这些结果表明了时间视觉处理和空间注意力分配之间的一种新的相互作用。我们的环境是动态的，因此视觉输入随时间变化。为了理解不断变化的信息，我们的视觉系统平衡了两个互补的过程：为了识别变化而进行的时间分离，以及为了识别时间一致性而进行的时间整合。当我们知道某种情况需要使用这两种操作中的一种或另一种时，我们就能够为此做好准备，这种准备可以在振荡脑活动中得到跟踪。在这里，我们展示了这种时间处理的准备如何能够在空间上得到集中。当我们期望整合或分割将出现在特定位置的视觉刺激时，负责该位置表示的视觉区域中的振荡脑活动会发生变化。通过这种方式，空间和时间机制相互作用，以支持自适应、高效的感知。
