Isolating neural mechanisms of voluntary temporal attention

To handle the continuous influx of visual information, temporal attention prioritizes visual information at task-relevant moments in time. We first introduce a probabilistic framework that clarifies the conceptual distinction and formal relation between temporal attention, linked to timing relevance, and temporal expectation, linked to timing predictability. Next, we present two MEG studies in which we manipulated temporal attention while keeping expectation constant, allowing us to isolate neural mechanisms specific to voluntary temporal attention. Participants were cued to attend to one of two sequential grating targets with predictable timing, separated by a 300 ms SOA. The first study used time-resolved steady-state visual evoked responses (SSVER) to investigate how temporal attention modulates anticipatory visual activity. In the pre-target period, visual activity (measured with a background SSVER probe) steadily ramped up as the targets approached, reflecting temporal expectation. Furthermore, we found a low-frequency modulation of visual activity, which shifted approximately 180 degrees in phase according to which target was attended. The second study used time-resolved decoding and source reconstruction to examine how temporal attention affects dynamic target representations. Temporal attention to the first target enhanced its orientation representation within a left fronto-cingulate region ~250 ms after stimulus onset, perhaps protecting it from interference from the second target within the visual cortex. Together these studies reveal how voluntary temporal attention flexibly shapes pre-target periodic dynamics and post-target routing of stimulus information to select a task-relevant stimulus within a sequence.