Phase Transfer Entropy between Frontal and Posterior Regions during Visual Spatial Attention

Voluntarily shifting attention to a location of the visual field improves the perception of stimulus at the attended location and suppresses information processing at unattended locations, something referred to as visual spatial attention. Previous studies have shown that alpha band phase synchronization between frontal and posterior regions was modulated by visual spatial attention. However, the causality of such long-range connectivity is still unknown, which makes it difficult to assess its relation to the underlying neural mechanisms of visual spatial attention. In this study, 64-channel scalp electroencephalography (EEG) was collected from 26 healthy adults when performing a visual spatial-cueing attention task, and a recently proposed algorithm, phase transfer entropy (PTE), was used to study the directed alpha phase interactions between frontal and posterior regions during attention orienting. We found that: (i) The PTE from frontal regions to posterior regions significantly increased after cue onset; (ii) The PTE from frontal regions (especially the right hemisphere) to posterior regions showed significant lateralization during late cue-target interval, with the greater PTE of contralateral frontal-to-posterior pair than that of ipsilateral pair relative to cue direction. These results suggest that alpha phase interactions might reveal top-down control signals from frontal to posterior regions during visual spatial attention, and support the right frontal regions as the causal role in top-down attentional control.