Cortical functional connectivity under different auditory attentional efforts.

Auditory attentional effort (AAE) could be tuned to different levels in a top-down manner, while its neural correlates are still poorly understood. In this paper, we investigate the cortical connectivity under different levels of AAE. Multichannel EEG signals were recorded from nine subjects (male/female=6=3) in an auditory discrimination task under low or high AAE. Behavioral results showed that subjects paid more attention under high AAE and detected the probe stimuli better than low AAE. Partial directed coherence (PDC) was used to study the cortical functional connectivity within the first 300 ms post-stimulus period which includes the N100 and P200 components in the event-related potential (ERP). Majority of the cortical connections were strengthened with the increase of AAE. The right hemispheric dominance of connectivity in maintaining auditory attention was found under low AAE, which disappeared when the AAE was increased, indicating that the right hemispheric dominance previously reported might be due to a relatively lower AAE. Besides, most cortical connections under high AAE were found to be from the parietal cortex to the prefrontal cortex, which suggested the initiative role of parietal cortex in maintaining a high AAE.