Neural entrainment to imagined rhythms in individuals with proficient imagery ability

Sensorimotor synchronization (SMS) involves the temporal coordination of motor movement with an external or imagined stimulus. Finger-tapping studies indicate better SMS performance with auditory or tactile stimuli compared to visual. However, the ability to synchronize with a visual rhythm can be improved by enriching stimulus properties (e.g., spatiotemporal content) or as a result of individual differences (e.g., one’s vividness of auditory imagery). We previously used a finger-tapping synchronization-continuation paradigm and showed that higher self-reported vividness of auditory imagery led to more consistent SMS when participants continued without a guiding visual rhythm. Here, we further examined the contribution of imagery to SMS performance by testing proficient imagers and including auditory or visual distractors during the continuation phase. While visual distractors had minimal effect, SMS consistency was significantly worse when auditory distractors were presented. Analysis of electroencephalography (EEG) revealed neural entrainment at the beat-related frequency, but only when visual or auditory distractors were present. Neural entrainment to the beat frequency positively correlated with SMS consistency in the presence of visual distractors, suggesting the potential utilization of auditory imagery and its role in supporting SMS performance. During continuation with auditory distractors, the neural entrainment showed an occipital electrode distribution suggesting the involvement of visual imagery. Unique to SMS continuation with auditory distractors, neural and sub-vocal (measured with electromyography) entrainment were found at the three-beat pattern frequency. In this most difficult condition, proficient imagers employed both beat- and pattern-related imagery strategies. However, this combination was not enough to restore SMS consistency to the same level observed with visual or no distractors. Combined, our results suggest that proficient imagers effectively utilized beat-related imagery in one modality when imagery in another modality was limited.