abstract Mathilde Bonnefond

Mathilde Bonnefond (Radboud University, Nijmegen, the Netherlands)

Left prefrontal cortex controls alpha phase adjustment in anticipation of predictable stimuli

Oscillatory alpha activity (8-12Hz) has been proposed to represent an active mechanism of functional inhibition over neuronal processing. More precisely, alpha oscillations would be associated with pulses of inhibition every ~100ms. Whether alpha phase can be top-down adjusted in order to improve information processing under appropriate experimental conditions remains unclear.  We carried out two experiments using magnetoencephalography, a working memory task involving distractors and a cross-modal (audio-visual) attention task. The time onset of all stimuli was predictable across trials. In addition to modulation in alpha power, we found pre-stimulus alpha phase to be adjusted in anticipation of predictable, relevant or irrelevant, stimuli in the visual domain. Moreover, alpha phase adjustment optimized the processing of stimuli, as assessed by stimulus-induced gamma activity and reaction times. Finally, alpha oscillations in the left prefrontal cortex controlled the adjustment of alpha phase in visual areas in both experiments. Our results confirm that alpha phase can be adjusted in anticipation of predictable stimuli and improve their processing and related behaviour. Modulation of anticipatory power and phase adds to the computational versatility of the alpha rhythm, since it allows for adjustment of the processing capabilities of the visual system on a fine temporal scale.