Changes in the frequency power spectrum of the human EEG during visual and kinesthetic imagery

Past research has provided evidence linking visual mental imagery to specific underlying neural activity. There have been few works examining links between motor imagery and corresponding neural reactivity. Neural activity during mental imagery has been reliably measured using electroencephalogram (EEG) methodology. The current study examined task dependent changes in EEG power during periods of baseline resting wakefulness, visual mental imagery of motor movements and kinesthetic mental imagery of motor movements. The main hypotheses were that baseline periods, with the eyes open and the eyes closed, and periods of mental imagery would have different distributions of EEG measured over the scalp. It was predicted that visual imagery would produce different patterns of EEG than kinesthetic imagery, and that genders would differ in the patterns of EEG recorded during baseline periods and during periods of mental imagery. The Movement Imagery Questionnaire was given to 20 males and 21 females for the purpose of selecting imagery tasks in which the participants reported they could image both visually and kinesthetically. Subsequently, the EEG of each participant was recorded while the individual successively relaxed with eyes-open, relaxed with eyes-closed and performed mental imagery of movement in the visual and kinesthetic modes. The EEG signals were digitally processed and evaluated for differences between the recording conditions. Results described different patterns of EEG power between eyes-open and eyes-closed periods of wakefulness and differences in patterns of EEG power between periods of resting wakefulness and mental imagery. Mental imagery of movement appears to be a neurally active state involving more EEG frequency bands than those previously reported. There is evidence to suggest that kinesthetic imagery elicits more cortical activation than visual imagery modes; however it remains unclear whether visual imagery and kinesthetic imagery are truly distinct processes. The present data provided some physical correlates with the mental imagery of movement. The problems associated with the interpretation of large data sets produced by the measurement of many variables were discussed.