Frontostriatal salience network expansion in individuals in depression.

Decades of neuroimaging studies have shown modest differences in brain structure and connectivity in depression, hindering mechanistic insights or the identification of risk factors for disease onset1. Furthermore, whereas depression is episodic, few longitudinal neuroimaging studies exist, limiting understanding of mechanisms that drive mood-state transitions. The emerging field of precision functional mapping has used densely sampled longitudinal neuroimaging data to show behaviourally meaningful differences in brain network topography and connectivity between and in healthy individuals2-4, but this approach has not been applied in depression. Here, using precision functional mapping and several samples of deeply sampled individuals, we found that the frontostriatal salience network is expanded nearly twofold in the cortex of most individuals with depression. This effect was replicable in several samples and caused primarily by network border shifts, with three distinct modes of encroachment occurring in different individuals. Salience network expansion was stable over time, unaffected by mood state and detectable in children before the onset of depression later in adolescence. Longitudinal analyses of individuals scanned up to 62 times over 1.5 years identified connectivity changes in frontostriatal circuits that tracked fluctuations in specific symptoms and predicted future anhedonia symptoms. Together, these findings identify a trait-like brain network topology that may confer risk for depression and mood-state-dependent connectivity changes in frontostriatal circuits that predict the emergence and remission of depressive symptoms over time.

Reliability and robustness of feedback-evoked brain-heart coupling after placebo, dopamine, and noradrenaline challenge.

External and internal performance feedback triggers not only neural but also cardiac modulations, suggesting communication between brain and heart during feedback processing. Using Cardio-Electroencephalographic Covariance Tracing (CECT), it has accordingly been shown that feedback-evoked centromedial single-trial EEG at the P300 latency intraindividually predicts subsequent changes in heart period - the so called N300H phenomenon. While previous findings suggest that the N300H depends on serotonin, its relationship to central dopamine and noradrenaline is currently unknown. Here, we tested (1) the psychometric properties of this CECT-based component and (2) its putative catecholaminergic mechanisms. N = 54 healthy male participants received either a α2-adrenoceptor antagonist (yohimbine, 10 mg; n = 18), D2-dopamine-receptor antagonist (sulpiride, 200 mg; n = 18), or a placebo (n = 18). Afterwards, they performed a gambling task with feedback after each trial, while EEG and ECG were recorded. Feedback successfully evoked a significant N300H both across all 54 participants and within each substance group. Importantly, we show that N300H can be reliably measured in a priori defined time windows with as few as 240 feedback trials and is relatively unaffected when removing extreme single-trial values. However, we could not find any significant substance effects on N300H magnitude as well as on univariate feedback-related measures (FRN, P300, heart period). Altogether, the N300H component proves as a robust and reliable marker of cortico-cardiac coupling evoked by feedback. Furthermore, these findings suggest a subordinate role of catecholamines (i.e., noradrenaline and dopamine) and sympathetic pathways in feedback-evoked brain-heart communication as measured with N300H.