Neurovascular coupling of inhibitory control in late-onset depression: a simultaneous EEG-fMRI study

Depression is a leading cause of disability that exerts an impact on neurocognitive functions. Individuals with major depressive disorder (MDD) have shown alterations of processes underlying response inhibition, which is the cognitive process that permits the suppression of habitual or natural behavioural responses to stimuli to select a more appropriate response that is coherent with the goal; these alterations have been correlated with cognitive deficits, especially in older adults. Electrophysiological (EEG) and functional magnetic resonance imaging (fMRI) studies have investigated the neuronal and hemodynamic process underlying inhibition through tasks measuring the ability to suppress a dominant response when non-target stimuli are shown and reported differences between healthy controls (HCs) and MDD subjects. However, these were unimodal studies that provided an incomplete picture of the phenomenon, due to the single technique sensitivity and limited by the characteristics of each technique itself. In this study, we performed an EEG-driven fMRI analysis to explore the different hemodynamic correlates of specific event-related potentials (ERPs) of inhibitory control in late-onset MDD during a visuomotor Go/No-Go task. The dataset was composed of 18 older adult HCs and 18 late-onset MDD patients. Behavioral analysis showed higher response time to target stimuli in inhibitory blocks and lower percentage of correct answers for target stimuli in MDD compared to HCs. ERP analysis revealed the inhibitory effect for both N2 and P3 in both groups. Moreover, EEG-driven fMRI analysis showed alterations in the MDD group in the superior temporal gyrus and cerebellar areas for N2 correlates, whereas in the supramarginal, left rolandic, and Heschl's areas for P3 correlates. The study showed the potentiality of the EEG-fMRI integration for investigating complex cognitive processes. Specifically, the EEG-driven fMRI analyses showed different correlates for separate cognitive processing steps, N2 and P3, highlighting differences between MDD and HC.