Spatial Attention and Temporal Expectation Exert Differential Effects on Visual and Auditory Discrimination.

Anticipation of an impending stimulus shapes the state of the sensory systems, optimizing neural and behavioral responses. Here, we studied the role of brain oscillations in mediating spatial and temporal anticipations. Because spatial attention and temporal expectation are often associated with visual and auditory processing, respectively, we directly contrasted the visual and auditory modalities and asked whether these anticipatory mechanisms are similar in both domains. We recorded the magnetoencephalogram in healthy human participants performing an auditory and visual target discrimination task, in which cross-modal cues provided both temporal and spatial information with regard to upcoming stimulus presentation. Motivated by prior findings, we were specifically interested in delta (1-3 Hz) and alpha (8-13 Hz) band oscillatory state in anticipation of target presentation and their impact on task performance. Our findings support the view that spatial attention has a stronger effect in the visual domain, whereas temporal expectation effects are more prominent in the auditory domain. For the spatial attention manipulation, we found a typical pattern of alpha lateralization in the visual system, which correlated with response speed. Providing a rhythmic temporal cue led to increased postcue synchronization of low-frequency rhythms, although this effect was more broadband in nature, suggesting a general phase reset rather than frequency-specific neural entrainment. In addition, we observed delta-band synchronization with a frontal topography, which correlated with performance, especially in the auditory task. Combined, these findings suggest that spatial and temporal anticipations operate via a top-down modulation of the power and phase of low-frequency oscillations, respectively.