Functional locus coeruleus imaging to investigate an ageing noradrenergic system
Ludwig et al., (2024). Communications Biology
Abstract
The locus coeruleus (LC), our main source of norepinephrine (NE) in the brain, declines with age and is a potential epicentre of protein pathologies in neurodegenerative diseases (ND). In vivo measurements of LC integrity and function are potentially important biomarkers for healthy ageing and early ND onset. In the present study, high-resolution functional MRI (fMRI), a reversal reinforcement learning task, and dedicated post-processing approaches were used to visualise age differences in LC function (N = 50). Increased LC responses were observed during emotionally and task-related salient events, with subsequent accelerations and decelerations in reaction times, respectively, indicating context-specific adaptive engagement of the LC. Moreover, older adults exhibited increased LC activation compared to younger adults, indicating possible compensatory overactivation of a structurally declining LC in ageing. Our study shows that assessment of LC function is a promising biomarker of cognitive aging.
Ludwig et al., (2021). Autonomic Neuroscience
Abstract
Transcutaneous auricular vagus nerve stimulation (taVNS), as a non-invasive brain stimulation technique may influence the locus coeruleus-norepinephrine system (LC-NE system) via modulation of the Vagus Nerve (VN) which projects to the LC. Few human studies exist examining the effects of taVNS on the LC-NE system and studies to date assessing the ability of taVNS to target the LC yield heterogeneous results. The aim of this review is to present an overview of the current challenges in assessing effects of taVNS on LC function and how translational approaches spanning animal and human research can help in this regard. A particular emphasis of the review discusses how the effects of taVNS may be influenced by changes in structure and function of the LC-NE system across the human lifespan and in disease.