“…These adjustments likely arise from multiple neuromodulatory systems, principally the locus-coeruleus (LC) norepinephrine system and basal forebrain cholinergic system (Joshi & Gold, 2020; Joshi, Li, Kalwani, & Gold, 2016; Reimer et al, 2016), that can affect either bottom-up or top-down information processing in the brain under different conditions. For example, relatively slow fluctuations in baseline or “tonic” arousal levels have been linked to modulation of sensory neurons (Heller, Schwartz, Saderi, & David, 2020; Lin, Asinof, Edwards, & Isaacson, 2019; McGinley, David, & McCormick, 2015; McGinley, Vinck, et al, 2015; Reimer et al, 2014; Schwartz, Buran, & David, 2020; Vinck, Batista-Brito, Knoblich, & Cardin, 2015) and changes in perceptual sensitivity in animal models and human subjects (Gelbard-Sagiv, Magidov, Sharon, Hendler, & Nir, 2018; McGinley, David, et al, 2015; Waschke, Tune, & Obleser, 2019), suggesting bottom-up effects. In contrast, relatively fast, event-driven “phasic” changes in arousal have shown inconsistent relationships to perceptual sensitivity in human subjects (de Gee et al, 2017, 2020).…”