Cortical activation and functional connectivity during a verbal fluency task in patients with chronic insomnia: A multi-channel NIRS study.

Patients with chronic insomnia exhibit varying degrees of cognitive dysfunction. Functional connectivity of different brain regions contributes to the understanding of underlying cognitive processes in the cerebral cortex. However, this has not yet been studied in patients with chronic insomnia. This study aimed to elucidate the differences between brain activity patterns in patients with chronic insomnia and healthy controls (HCs) using a verbal fluency task (VFT). We recruited 84 patients with chronic insomnia and 81 HCs. Oxy-haemoglobin (Oxy-Hb) concentrations in the brains of the participants were monitored using functional near-infrared spectroscopy (fNIRS) while performing the VFT. During the task period, no significant difference was observed between the VFT results of the two groups; patients with chronic insomnia showed significantly less cortical activation in haemodynamic responses of oxy-Hb at channels and brain regions mainly located in the prefrontal cortex compared to HCs (FDR-corrected p < 0.05). Moreover, the average channel-to-channel connectivity strength of patients in the chronic insomnia group was lower than that of those in the HC group (t = −6.717, p < 0.001). Our study provides neurological evidence for the dynamic detection of executive function in patients with chronic insomnia. Compared to HCs, patients with chronic insomnia exhibit weaker levels of brain activity and reduced task-related functional connectivity. [ABSTRACT FROM AUTHOR]