Anxiety-related impairment of inhibition during early sensory processing: an MMN/MOR study

When a behavioral task becomes attentionally demanding, anxiety-prone individuals become more susceptible to task-irrelevant sensory events. Attentional control theory proposes that this susceptibility arises from impairments in the inhibition function, a central executive function that regulates responses to sensory stimuli. This study examined whether anxiety-related impairment of inhibition affects early sensory processing of task-irrelevant auditory stimuli, as measured by mismatch negativity (MMN), an early pre-attentive electroencephalographic response evoked by abrupt auditory changes. MMNs were recorded using an oddball paradigm while participants performed a visual task of varying difficulty. The results showed that the enhancement of MMN to a task-irrelevant high-frequency tone at a latency within 250 ms was significantly associated with trait anxiety when the visual task became more attentionally demanding, suggesting that impaired inhibition intrudes on early sensory processing. Furthermore, time-frequency analyses revealed that power enhancements of mismatch oscillatory responses in the alpha/low-beta band, occurring approximately up to 450 ms after stimulus onset, were significantly correlated with trait anxiety under high attentional demand. These findings suggest that compensatory top-down mediated sensory suppression of task-irrelevant events occurs through early sensory processing, along with impaired distractor inhibition reflected in MMN. This study proposes that impaired inhibition and compensatory sensory suppression in anxiety-prone individuals occur in a multi-tiered manner, even at the pre-attentive level.