Event-related desynchronization (ERD) in the alpha band during a hand mental rotation task

Recent studies have demonstrated that mentally rotating the hands involves participants engaging in motor imagery processing. However, far less is known about the possible neurophysiological basis of such processing. To contribute to a better understanding of hand mental rotation processing, event-related spectral perturbation (ERSP) methods were applied to electroencephalography (EEG) data collected from participants mentally rotating their hands. Time-frequency analyses revealed that alpha-band power suppression was larger over central-parietal regions. This is in accordance with motor imagery findings suggesting that the motor regions may be involved in processing or detection of kinaesthetic information. Furthermore, the presence of a significant negative correlation between reaction times (RTs) and alpha-band power suppression over central regions is illustrated. These findings are consistent with the neural efficiency hypothesis, which proposes the non-use of many brain regions irrelevant for the task performance as well as the more focused use of specific task-related regions in individuals with better performance. These results indicate that ERSP provides some independent insights into the mental rotation process and further confirms that parietal and motor cortices are involved in mental rotation.