Modeling the Role of the Alpha Rhythm in Attentional Processing during Distractor Suppression.

Abstract

Recent experimental results suggest that alpha oscillations in brain neuroelectrical activity do not merely represent an idling phenomenon but actively participate in attention to suppress distractors and reduce cognitive workload. However, the exact mechanism responsible for this attentional processing is still a matter of research. In this work, we propose a simple mechanism for distractor suppression using a neural mass model of oscillating, interconnected cortical regions, based on alpha oscillations and their interaction with the gamma rhythm. Essentially, the model distinguishes between certain "sensory" areas, where stimuli are coded and represented via gamma oscillations, a downstream "detection" area dedicated to processing these stimuli, and a "control" region that generates the alpha rhythm. Unattended stimuli in a sensory area can be suppressed by simply imposing an alpha rhythm that is out of phase compared with the detection layer. A sensitivity analysis performed on a simple paradigmatic model emphasizes the robustness of the proposed mechanism versus parameter changes. Moreover, a more complex example (concerning spatial attention, where objects are represented through a Gestalt proximity rule) supports the capacity of the mechanism to suppress distractors in multi-unit networks. The model aligns with several experimental results and can be further utilized to investigate cognitive alterations in pathological conditions, such as schizophrenia, characterized by dysfunction in the gamma rhythm.