Galas, L. | bioRxiv Science

bioRxiv2025

Theta-rhythmic attentional exploration of space

Attention facilitates stimulus processing by selecting specific locations (spatial attention) or features (feature-based attention). It can be sustained on a given location or feature, or re-oriented between locations or between features, enabling attentional exploration. Sustained attention was associated with alpha (8-12Hz1-4) oscillations. More recently, authors suggested that exploratory attention was instead related to theta (4-7Hz; for review5-7). To date, there is no systematic evaluation of attentional exploration across stimulus dimensions (space, features) in relation to theta oscillations. Using attentional cueing and electroencephalography (EEG) in humans, we assessed exploration of stimulus dimension during the (1) precue-to-stimulus (first attentional orienting) and (2) post-stimulus (during stimulus processing) trial periods. In the precue-to-stimulus period, we classified the cued dimension (attending to a location/feature) from EEG topographies to assess the neural dynamics of sustained and exploratory attentional orienting. Temporal generalization matrices showed oscillatory patterns of classification accuracies across time. When attention was sustained on a cued location but explored the feature dimension as the target feature was unknown, only the alpha frequency was observed. When attention was sustained on a cued feature but explored locations, both alpha and theta frequencies were observed. Focusing on post-stimulus theta oscillations revealed increased theta power in invalid trials (attention reorients from the precued distractor location/feature to the target -exploration) relative to valid trials in both feature-based and spatial attention conditions. Post-stimulus theta oscillations further predicted behavioral performance. Together, our results show that while alpha oscillations are associated with sustained attention regardless of the attended dimension, theta oscillations are specifically related to spatial exploration.

neuroscience↗

bioRxiv2023

Attention rhythmically shapes sensory tuning

Attention is key to perception and human behavior, and evidence shows that it periodically samples sensory information (<20Hz). However, this view has been recently challenged due to methodological concerns and gaps in our understanding of the function and mechanism of rhythmic attention. Here we used an intensive [~]22-hour psychophysical protocol combined with reverse correlation analyses to infer the neural representation underlying these rhythms. Participants performed a task in which covert spatial (sustained and exploratory) attention was manipulated, and then probed at various delays. Our results show that sustained and exploratory attention periodically modulate perception via different neural computations. While sustained attention suppresses distracting stimulus features at the alpha ([~]12Hz) frequency, exploratory attention increases the gain around task-relevant stimulus feature at the theta ([~]6Hz) frequency. These findings reveal that both modes of rhythmic attention differentially shape sensory tuning, expanding the current understanding of the rhythmic sampling theory of attention. Significance statementFor the past decade, low-frequency rhythms were described in attentional performance. Here, we go beyond description and assess the underlying neural computations in the sensory system. We used an intensive psychophysical protocol combined with reverse correlation analysis to infer the systems sensitivity to and selectivity for stimulus feature (orientation) across time, and for two attention modes, i.e., sustained and exploratory attention. Our results show that signal enhancement as well as suppression occurred rhythmically, depending on the attentional state, leading to enhanced and improved performance phases - sustained and exploratory attention modes differentially shape the sensory tuning to stimulus feature.

neuroscience↗