Department of Psychological and Brain Sciences, Boston University, Boston, MA, USA.
Department of Psychology, New York University, New York, NY, USA.
Nat Commun. 2024 Oct 21;15(1):9061. doi: 10.1038/s41467-024-53406-y.
We can often anticipate the precise moment when a stimulus will be relevant for our behavioral goals. Voluntary temporal attention, the prioritization of sensory information at task-relevant time points, enhances visual perception. However, the neural mechanisms of voluntary temporal attention have not been isolated from those of temporal expectation, which reflects timing predictability rather than relevance. Here we use time-resolved steady-state visual evoked responses (SSVER) to investigate how temporal attention dynamically modulates visual activity when temporal expectation is controlled. We recorded magnetoencephalography while participants directed temporal attention to one of two sequential grating targets with predictable timing. Meanwhile, a co-localized SSVER probe continuously tracked visual cortical modulations both before and after the target stimuli. We find that in the pre-target period, the SSVER gradually ramps up as the targets approach, reflecting temporal expectation. Furthermore, we find a low-frequency modulation of the SSVER, which shifts approximately half a cycle in phase according to which target is attended. In the post-target period, temporal attention to the first target transiently modulates the SSVER shortly after target onset. Thus, temporal attention dynamically modulates visual cortical responses via both periodic pre-target and transient post-target mechanisms to prioritize sensory information at precise moments.
我们经常可以预测到刺激对于我们行为目标相关的确切时刻。自愿性时间注意力，即在任务相关时间点对感觉信息的优先处理，增强了视觉感知。然而，自愿性时间注意力的神经机制尚未从时间预期的机制中分离出来，时间预期反映的是时间可预测性，而不是相关性。在这里，我们使用时间分辨稳态视觉诱发电位（SSVER）来研究当时间预期受到控制时，时间注意力如何动态地调节视觉活动。当参与者将时间注意力指向具有可预测时间的两个顺序光栅目标中的一个时，我们记录了脑磁图。同时，一个局部的 SSVER 探针在目标刺激之前和之后连续跟踪视觉皮层的调制。我们发现，在前目标期间，SSVER 逐渐上升，反映了时间预期。此外，我们发现 SSVER 的低频调制，根据所关注的目标，其相位大约偏移半个周期。在后目标期间，对第一个目标的时间注意力在目标出现后不久短暂地调节了 SSVER。因此，时间注意力通过周期性的前目标和短暂的后目标机制来动态地调节视觉皮层反应，以便在精确的时刻优先处理感觉信息。
