This study investigated the architecture and neural activity of white matter functional networks (WMFNs) in individuals with opioid use disorder (OUD) after prolonged abstinence, compared with healthy controls (HCs).

Blood oxygen level-dependent signals in white matter were analyzed using a data-driven k-means clustering approach across individuals with OUD at baseline (OUD1), the same individuals after prolonged abstinence at follow-up (OUD2), and HCs.

In OUD1, the deep frontoparietal network was fragmented into the superior longitudinal fasciculus network and anterior corona radiata network; this organization partially recovered in OUD2, becoming more similar to HCs. OUD1 also showed hyperactivation in the deep frontal network and hypoactivation in the frontotemporal-parietal network, with frontotemporal-parietal activity negatively correlated with years of opioid use.

OUD is associated with disrupted architecture of WMFNs and altered neural activity, whereas prolonged abstinence may promote partial network restoration. These findings highlight the neuroplastic potential of WMFNs during recovery and provide insights into the neural mechanisms underlying OUD and abstinence-related rehabilitation.

Impaired emotional processing is a core feature of schizophrenia (SZ). Consistent findings suggested that abnormal emotional processing in SZ could be paralleled by a disrupted functional and structural integrity within the fronto-limbic circuitry. The effective connectivity of emotional circuitry in SZ has never been explored in terms of causal relationship between brain regions. We used functional magnetic resonance imaging and Dynamic Causal Modeling (DCM) to characterize effective connectivity during implicit processing of affective stimuli in SZ.

We performed DCM to model connectivity between amygdala (Amy), dorsolateral prefrontal cortex (DLPFC), ventral prefrontal cortex (VPFC), fusiform gyrus (FG) and visual cortex (VC) in 25 patients with SZ and 29 HC. Bayesian Model Selection and average were performed to determine the optimal structural model and its parameters.

Analyses revealed that patients with SZ are characterized by a significant reduced top-down endogenous connectivity from DLPFC to Amy, an increased connectivity from Amy to VPFC and a decreased driving input to Amy of affective stimuli compared to HC. Furthermore, DLPFC to Amy connection in patients significantly influenced the severity of psychopathology as rated on Positive and Negative Syndrome Scale.

Results suggest a functional disconnection in brain network that contributes to the symptomatic outcome of the disorder. Our findings support the study of effective connectivity within cortico-limbic structures as a marker of severity and treatment efficacy in SZ.