Proximity to Visual Stimuli Reduces Post-Saccadic Alpha Lateralisation

Posterior alpha lateralisation is a well-established marker of visual spatial attention, with growing evidence suggesting that it may also be linked to oculomotor planning and execution. However, saccades also result in a change in visual input to the fovea, which could be linked to lateralised posterior alpha. In this study, we investigate the interplay between saccade-induced foveal input changes and lateralised posterior alpha by analysing saccades from the cue period of a Posner task and the active feedback period of a neurofeedback task, where visual stimuli were present on screen. Specifically, we examine the impact of saccade landing proximity to visual stimuli and saccade amplitude on post-saccade alpha lateralisation. Consistent with previous research, we observe a general post-saccade alpha lateralisation across both tasks. Importantly, we find that alpha lateralisation is reduced in the neurofeedback task when saccades land close to visual stimuli compared to those landing further away, while saccade amplitude has no significant effect. This investigation highlights the importance of controlling for both eye movements and visual stimuli when investigating alpha lateralisation in fixational tasks. Moreover, it shows how both oculomotor and afferent processing mechanisms affect posterior alpha lateralisation.