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. Author manuscript; available in PMC: 2023 Jan 1.
Published in final edited form as: Trends Cogn Sci. 2021 Nov 16;26(1):38–52. doi: 10.1016/j.tics.2021.10.009

Figure 1, Key Figure. Locus coeruleus–noradrenergic neuromodulation shapes patterns of thalamocortical synchronization during attention.

Figure 1, Key Figure.

(A) Anatomically and functionally defined locus coeruleus ensembles innervate different cortical and subcortical targets (see colored cells/projections [circles/arrows]), including the thalamus and frontoparietal network. (blue; grey). During inattentiveness, low noradrenaline levels are linked to rhythmic burst firing in thalamic alpha generators (see C). Alpha-rhythmic activity (~8–12 Hz) in thalamocortical attention networks indicates a state of relative inhibition (see high amplitude low-frequency oscillation [light blue]) (B) Behaviorally relevant events elicit a transient increase in locus coeruleus activity. Elevated noradrenaline (NA) levels modulate cortical synchronization by shifting thalamic pacemakers from a rhythmic firing pattern to a mode of activity that allows for reliable information transfer (single-spike firing; see C). Neural activity in thalamocortical attention networks is desynchronized (dark blue), supporting the processing of attended stimuli. (C) Noradrenaline depolarizes thalamic neurons and abolishes the rhythmic burst firing that is linked to thalamocortical alpha rhythms (reproduced, with permission, from [9]). (D) Pupil-indexed noradrenergic neuromodulation is related to cortical low-frequency desynchronization. (left) Compared to perceptually matched control stimuli (CS−), fear-conditioned stimuli (CS+) elicit a transient pupil dilation, a marker of locus coeruleus activity (Box 1). (middle) Concurrent electroencephalography recordings reveal an arousal-related alpha-beta desynchronization at posterior electrodes (topography shows averaged activity between 0.5–1.5 s and 8–20 Hz [grey horizontal bar]). (right) Larger pupil dilation is associated with more alpha-beta desynchronization (i.e., more negative values), indicating an association between proxies of noradrenergic neuromodulation and cortical synchronization (reproduced, with permission, from [7]). Credits: Sagittal brain section, adapted from Patrick J. Lynch under a Creative Commons Attribution 2.5 License 2006.