Degree centrality alterations in different frequency bands in chronic insomnia: A resting-state fMRI study

Abnormal spontaneous neural activity in chronic insomnia (CI) has been identified in previous neuroimaging studies. However, whether the spontaneous neural activity is frequency-specific in CI is largely unknown.

We used resting-state functional magnetic resonance imaging (rs-fMRI) and degree centrality (DC) analysis to examine spontaneous neural activity in 37 CI patients and 20 healthy controls (HCs) across four frequency bands: slow-5 (0.012-0.031 Hz), slow-4 (0.031-0.081 Hz), slow-3 (0.081-0.224 Hz), and slow-2 (0.224-0.25 Hz). Partial correlation analysis was used to explore the relationship between abnormal DC values and clinical scales.

In the slow-5 band, CI patients showed reduced DC in the occipital cortex compared with HCs. In the slow-4 band, CI patients displayed lower DC in the left middle temporal gyrus. In the slow-3 and slow-2 bands, decreased DC was primarily located in the frontal cortex. Moreover, CI patients showed higher DC in the right middle frontal gyrus and dorsolateral part of the superior frontal gyrus at the slow-4, slow-3, and slow-2 bands. Increased DC was also observed in the right median cingulate and paracingulate gyri at the slow-3 band. Furthermore, DC values in the right MFG at the slow-4 band were positively correlated with Mini-Mental State Examination scores.

Our findings suggest that CI patients exhibit widespread, frequency-specific alterations in brain activity, offering insights into the neurobiological mechanisms of CI.