Adaptive executive control indexed by frontal theta beta ratio dynamics and trial-level EEG during ecologically valid tasks in schizophrenia

Schizophrenia is characterized by persistent executive dysfunction and atypical engagement of prefrontal circuits underlying attentional control. However, the neural dynamics of executive processing during ecologically relevant tasks remain underexplored. This study examined frontal theta/beta oscillatory patterns and trial level EEG responsiveness as indices of adaptive cognitive control in schizophrenia compared to healthy controls. Thirty adults with schizophrenia (M age = 39.9, SD = 9.10 years) and a matched healthy control group (N = 30; M age = 32.25, SD = 6.50 years) underwent quantitative EEG during an eyes-open resting state and while performing two executive tasks: an augmented reality visuomotor challenge (LCAR) and a mobile guided daily routine task (B2B). Frontal theta/beta ratios (TBR) at Fz and Cz indexed attentional engagement. Trial level responsiveness was assessed via discrete Stimulus Response Events (SREs). Results: Both LCAR and B2B elicited significant TBR increases relative to eyes open rest at midline frontal sites (p < .001), reflecting elevated executive demand. Compared to healthy controls, participants with schizophrenia exhibited higher baseline TBR and reduced modulation across task segments. In contrast, controls showed stronger SRE linked variability and greater memory gains, indicating more efficient task locked cognitive adaptation. Age related effects were also observed, with participants under 40 years showing higher resting TBR at Fp1 (p =.01). Conclusion: Findings advance understanding of prefrontal theta/beta modulation as a neurophysiological marker of adaptive executive control during complex, ecologically valid tasks. By integrating real-world paradigms with trial level EEG analyses, this study contributes to models of dynamic information processing and cognitive resource allocation in schizophrenia. Keywords: schizophrenia; healthy controls; theta/beta ratio; QEEG; executive function; augmented reality; neural biomarkers