Distinct patterns of cortical activation and functional connectivity in children with high-functioning autism during a verbal fluency task: a comparative fNIRS study.

Abstract

Objective: Children with High-Functioning Autism (HFA) often show marked deficits in executive functioning, particularly during verbal fluency tasks (VFTs). These behavioral impairments are believed to stem from neurophysiological abnormalities in the prefrontal cortex (PFC) functioning, characterized by atypical activation patterns and disrupted functional connectivity. This study utilized functional near-infrared spectroscopy (fNIRS) to investigate hemodynamic responses and connectivity metrics during VFT performance. By comparing children with HFA to age-matched typically developing (TD) controls, this study aimed to clarify the neural mechanisms underlying the executive control of language production in HFA.

Methods: The sample included 29 children who met diagnostic criteria for HFA and 26 TD controls. All participants had a Full-Scale Intelligence Quotient of 70 or higher and were matched for age and cognitive ability. During a standardized phonemic VFT, cortical hemodynamics were continuously monitored using a 19-channel fNIRS system, with analyses focusing on changes in oxygenated hemoglobin concentration within PFC regions.

Results: Compared with TD controls, children with HFA exhibited reduced cortical activation across multiple prefrontal regions, including channels 1 (t = -2.975, p = 0.017), 2 (t = -4.320, p = 0.001), 3 (t = -3.381, p = 0.012), 9 (t = -3.127, p = 0.014), and 19 (t = -3.279, p = 0.012). These regions correspond anatomically to the inferior prefrontal gyrus, frontopolar cortex, and dorsolateral PFC. Functional connectivity analyses demonstrated significantly reduced interregional coupling in the HFA group (p < 0.001), with mean connectivity values of 0.512 (SD = 0.076) compared with 0.566 (SD = 0.069) in TD participants. Furthermore, Oxy-Hb changes in prefrontal channels 1 (r = -0.424, p = 0.022), 2 (r = -0.432, p = 0.019), and 3 (r = -0.394, p = 0.034) were negatively correlated with Social Responsiveness Scale total scores, indicating that weaker prefrontal activation was associated with greater social impairment.

Conclusion: The results reveal distinct cortical activation and functional connectivity alterations in children with HFA during VFTs. These findings support the hypothesis that disrupted interregional brain coordination underlies executive difficulties in language production in HFA children, who exhibit reduced PFC activation and weaker interregional functional connectivity during the VFT.