Diurnal rhythmicity modulates self-blaming behaviours and neural processing of autobiographical guilt memories in the trait-like and state-like manner

Increasing evidence implicates late chronotype and higher distinctness as two diurnal dimensions associated with a risk for affective dysregulation. Nonetheless, the underlying behavioural and neural mechanisms remain poorly understood. Previous works in depressive and anxious populations have demonstrated an important role of maladaptive self-blaming processes, with pivotal contributions from superior anterior temporal lobes (sATL), involved in social conceptual knowledge, and subgenual anterior cingulate cortex (sgACC), related to self-worth and social affiliative processing. In the current study, we first tested how diurnal rhythm characteristics were associated with self-blaming emotions and related coping mechanisms through hypothetical social scenarios where participants or their close friends acted towards one another against social norms. Secondly, to probe alterations in the neural correlates of self-blaming, the participants underwent functional neuroimaging during reliving of autobiographical guilt memories. On the behavioural level, late chronotypes demonstrated decreased self-distancing and contextually-maladaptive blaming patterns, i.e. increased blaming of the action recipients rather than the agents. This was paralleled by decreased self-blame-related activity in the sATL and sgACC. Distinctness was associated with altered task-dependent sATL connectivity with hippocampus, brainstem and cerebellum. Importantly, some of the neuroimaging findings reflected interactions between the diurnal rhythm characteristics and time-of-day. As such, the current work provides plausible correlates of adverse emotional outcomes in late chronotypes. Furthermore, it suggests that affective processing reflects an interplay between stable trait-like characteristics and dynamic state-like processes varying across the day, contributing to fine-grained understanding of how emotional cognition is embedded in the brain.