Optimized Simultaneous Assessment of Subcortical and Cortical Auditory Responses Through a Frequency-Tagged Roving...

Assessment of auditory-evoked responses across multiple stages of the ascending auditory pathway provides complementary insights into neural integrity for research and clinical contexts. However, traditional approaches, constrained by conflicting optimal parameters, require separate sessions for different response types, limiting efficiency and preventing simultaneous multi-level assessment, while evidence of individual-level sensitivity and reliability remains limited. We aimed to develop and validate a paradigm enabling concurrent, single-subject assessment of frequency-following responses (FFRs), auditory steady-state responses (ASSRs), and event-related potentials (ERPs) spanning subcortical to cortical levels. Two amplitude-modulated tones (carriers at 220/440 Hz, modulated at 40/80 Hz) were presented in a roving sequence so that each tone served as both standard and deviant, and EEG was recorded using a two-electrode montage (Fz, Cz) EEG setup. In 32 healthy participants, the paradigm achieved 100% sensitivity for high-frequency FFRs and gamma-band ASSRs, confirmed by permutation-based spectral analysis. Machine-learning classification distinguished stimulus conditions from resting state based on N1 and sustained negativity in all participants (32/32), confirming robust single-subject detection of obligatory cortical responses. Directional asymmetry was observed in transition responses: ascending frequency transitions predominantly elicited enhanced N1-P2-like responses (32/32), whereas descending transitions evoked mismatch negativity-like (MMN-like) responses in 30/32 participants. Recording-duration analysis showed that overall detection sensitivity across response components reached 0.91 after 27 min of recording. Collectively, these findings indicate that the frequency-tagged roving paradigm provides a framework for characterizing auditory processing across hierarchical levels within a single session, supporting potential use in future experimental and translational studies.