Functional and Structural Lesion Network Mapping: Insights Into Acquired Brain Injury and Insomnia

Insomnia disorder is the most reported sleep disorder and can negatively affect daily functioning. Acquired brain injuries can lead to insomnia disorder. Limited research has explored a causal link between brain networks and insomnia symptoms in this population. This study replicated a lesion network mapping methodology of an insomnia study (Helquist et al., 2024) and extended it to examine structural networks linked to insomnia symptoms in individuals with acquired brain injuries. Traced lesions (N =44) were used as seed regions to compare against normative functional and structural network data. For functional analyses, we used resting state fMRI scans from a healthy young adult cohort (N =1,000; Holmes et al., 2015), whereas structural analyses leveraged normative tractography diffusion-weighted MRI data from a healthy adult cohort (N = 180; Thiebaut de Schotten & Nachev, 2020). Functional and structural network analyses were conducted to examine convergence and divergence between networks associated with insomnia symptoms. Whereas Helquist and colleagues (2024) observed a functional network hub stemming from the anterior insula, we observed a functional network hub stemming from the anterior cingulate/paracingulate region. Both of these regions are part of the salience network, suggesting a distributed regulatory network that may be disrupted in individuals with insomnia. We also observed mean disconnection in the cerebellar peduncle and the anterior limb of the internal capsule tracts, which are associated with regulatory circuitry that may affect sleep-related processes. Overall, these findings suggest a distributed functional and structural regulatory network that, when disrupted, may dysregulate arousal, autonomic, and state transitions that can be associated with insomnia. Based on these observations, clinicians should integrate cognitive, emotional, and physiological factors in their assessments and interventions when working with insomnia patients.