Hemispheric Asymmetry of Globus Pallidus Explains Reward-related Posterior Alpha Modulation in Humans: Subcortical modulation of visual alpha oscillations

Abstract Although basal ganglia (BG) functions have been widely explored in relation to motor control, recent evidence suggests that their mechanisms extend to the domain of attentional switching. We here investigated the BG involvement in reward related top-down control of visual alpha-band oscillations (8 – 13 Hz), which have been linked to the mechanisms supporting the allocation of spatial attention. Given that items associated with contextual saliency (e.g. monetary reward or loss) attract attention, it is not surprising that alpha oscillations are further modulated by the saliency properties of the visual items. The executive network controlling such reward-dependent modulations of oscillatory brain activity has yet to be elucidated, and likely relies on the contribution of subcortical regions. To uncover this, we investigated whether derived measures of basal ganglia (BG) structural asymmetries could predict interhemispheric modulation of alpha power, during a spatial attention task. We show that volumetric lateralization of the globus pallidus (GP) significantly explains individual hemispheric biases in alpha power modulation. Importantly, this effect varied as a function of value-saliency parings in the task. We hence provide compelling evidence suggesting that the GP in humans is a node within the executive control network, implicated in reward related top-down control of visual alpha oscillations during saliency processing.