A meta-analytic review of multisensory imagery identifies the neural correlates of modality-specific and modality-general imagery

Abstract

The relationship between imagery and mental representations induced through perception has been the subject of philosophical discussion since antiquity and of vigorous scientific debate in the last century. The relatively recent advent of functional neuroimaging has allowed neuroscientists to look for brain-based evidence for or against the argument that perceptual processes underlie mental imagery. Recent investigations of imagery in many new domains and the parallel development of new meta-analytic techniques now afford us a clearer picture of the relationship between the neural processes underlying imagery and perception, and indeed between imagery and other cognitive processes. This meta-analysis surveyed 65 studies investigating modality-specific imagery in auditory, tactile, motor, gustatory, olfactory, and three visual sub-domains: form, color and motion. Activation likelihood estimate (ALE) analyses of activation foci reported within- and across sensorimotor modalities were conducted. The results indicate that modality-specific imagery activations generally overlap with-but are not confined to-corresponding somatosensory processing and motor execution areas, and suggest that there is a core network of brain regions recruited during imagery, regardless of task. These findings have important implications for investigations of imagery and theories of cognitive processes, such as perceptually-based representational systems.

Keywords: embodied cognition; imagery; imagination; modality-independent; modality-specific; semantic memory.

Figure 1

The general imagery network (cool colors) was primarily left-lateralized, with bilateral activations in superior parietal regions. A conjunction analysis of studies employing complex and resting state baselines found nine clusters (red) within the general imagery network that were active across all imagery conditions, regardless of baseline task.

Figure 2

Extent-thresholded clusters of voxels reaching pN < 0.05 significance in the auditory (AUD), motor (MTR), tactile (TAC), gustatory (GUS), olfactory (OLF), visual form (VFO), visual color (VCO) and visual motion (VMO) imagery ALE maps are depicted in warm values. Corresponding primary sensorimotor cortices are depicted in violet. Overlapping regions are depicted in pink/white.