Music and Visual Imagery: Electroencephalographic Evidence of General and Modality-Specific Activity Patterns

Abstract

There is a substantial corpus of evidence about the shared brain mechanism between imagery and perception. However, the psychophysiological exploration concerning possible mechanisms underlying modality-independent mental imagery and how much it involves or depends on other cognitive processes, such as attention and memory, is still scant. To address this, we performed an electroencephalographic (EEG) study to compare brain activity related to auditory/musical and visual imagery to identify shared and specific activity patterns. The electrical brain activity of 12 musicians was measured while they perceived or imagined either auditory or visual stimuli with two levels of complexity. Mean power differences were calculated between tasks and conditions for alpha, beta, and gamma bands. For the alpha band, an increase in mean relative power was observed in occipital and parietal areas throughout the paradigm. Regarding level of complexity of the imagery tasks, same-modality contrasts (i.e., auditory simple vs. auditory complex) showed small-magnitude differences in power that were only significant for a few locations along the midline. However, when comparing across imagery modalities (i.e., auditory simple vs. visual simple), the significantly different locations increased in number and were mainly distributed in central and occipital regions, where differences were positive for mean alpha power and negative for beta and gamma bands. With respect to resting (baseline) power, the main differences were observed as a wider distribution of beta power increments in relation to visual imagery tasks, and similarities were identified for both auditory and visual imagery tasks as an increase in gamma power in right frontal locations, increased frontal and pre-frontal beta power, and some bilateral parietal increased beta power. These results seem to support the hypothesis that mental imagery, to some extent, involves areas related to memory retrieval, attention, semantic processing, and motor preparation, in addition to the primary areas corresponding to each sensory modality.