Subjects: Psychology >> Cognitive Psychology submitted time 2024-06-17
Abstract： Major depressive disorder (MDD) is characterized by significant and lasting sadness. Previous studies have indicated that cognitive deficits, particularly in cognitive flexibility, are one of the core features of MDD, and the impairment pattern may play a key role in the onset and development of MDD. Cognitive flexibility, as a key component of cognitive function, often manifests as impaired in MDD patients, evidenced by rigid thinking and difficulty in flexibly switching among negative stimuli. Research suggests that cognitive inflexibility to emotional information may underlie the chronicity of negative emotional states in MDD./t/nWhile previous neuropsychological tests and clinical observations have shown that patients with MDD exhibit abnormal cognitive flexibility, behavioral studies have failed to reach a consensus on whether cognitive flexibility is impaired in both non-emotional and emotional stimuli in patients with MDD. It is suggested that integrating more precise neurophysiological measures could offer clearer insights into the mechanisms of cognitive inflexibility in MDD. Given the established link between the theta, alpha and beta bands and cognitive flexibility, the non-phase-locked activities that occur during task switching, which may be ignored in ERPs studies, may hold significant importance. Therefore, it is still necessary to further conceptualize EEG as multi-dimensional time-frequency signals to capture the changes of neural oscillations during task switching. Since time-frequency analysis offers temporal context while analyzing frequency components, the analysis of time-varying signals becomes more intuitive and comprehensible. Therefore, this study aims to employ time-frequency analysis to scrutinize the alterations of ERS/ERD in the theta, alpha and beta bands during both non-emotional and emotional task switching in patients with MDD, and explore the time-frequency characteristics that may indicate cognitive inflexibility in patients with MDD./t/nA demographically matched cohort of 74 MDD patients and 72 healthy control (HC) subjects completed both non-emotional and emotional task switching paradigms, with behavioral and electroencephalogram data being collected simultaneously. Neural oscillation activities of θ, α and β bands were analyzed as indices of brain electrical time-frequency dynamics, with their event‐related synchronization (ERS) or event‐related desynchronization (ERD) analyzed by 2 (group: MDD vs. HC) ×2 (paradigm: non-emotional vs. emotional) ×2 (task: repeat vs. switch) ×4 (region of Interest: frontal, central, parietal, occipital) repeated-measures ANOVA to compare the group differences in power across frequency bands./t/nOur results showed that the MDD group made more errors and took longer to complete the task-switching paradigms compared with the HC group. Specifically, the MDD group had significantly smaller θ-ERS in all regions of interest during non-emotional repeat and switch tasks, and significantly smaller θ-ERS in the frontal and central regions during emotional tasks. Additionally, the energy difference of θ band in the parieto-occipital region was significantly larger during emotional task switching. The MDD group had significantly smaller α-ERD in the non-emotional task switching paradigm, significantly smaller β-ERD in non-emotional repeat task, and significantly smaller β-ERD in both emotional tasks./t/nThe study concludes that patients with MDD exhibits impaired cognitive flexibility in response to both neutral stimuli and negative stimuli. Cognitive inflexibility in response to non-emotional stimuli is associated with less θ-ERS and excessive activity of α-ERD and β-ERD. Similarly, cognitive inflexibility in response to emotional stimuli is associated with less θ-ERS and excessive activity of β-ERD in MDD, with β-ERD emerging as a potentially sensitive biomarker for impaired cognitive flexibility in MDD. This study sheds new light on the understanding of impaired cognitive flexibility in MDD and further clarifies the underlying neural oscillatory mechanism of impaired cognitive flexibility.
Peer Review Status:
Awaiting Review
Hits
Hits
Downloads
Comment