Neural substrates of perception and imagery revealed by fMRI: a pilot study

Visual mental imagery, the subjective experience of “seeing” in the absence of sensory input, has long been studied in relation to perception. While considerable evidence points to shared neural mechanisms, the precise nature of their overlap and divergence remains an area of active investigation. The present fMRI study examined brain activation patterns and functional roles of distinct regions during the perception and imagery of animals, utilising a sparse temporal sampling paradigm to control for auditory interference. Seven participants (2 males, 5 females; mean age=22.57, SD=0.48) participated in the study. Perception and imagery tasks were conducted separately within a single session to minimise fatigue and motion artefacts. BOLD signals were preprocessed and analysed using SPM12, employing paired t-tests and repeated measures ANOVA. The analysis utilised an uncorrected threshold of p<0.001 at the voxel level, combined with cluster-level family-wise error correction at p<0.05. Results revealed substantial overlap in neural substrates, with perception uniquely engaged in the right medial superior frontal gyrus, suggesting heightened top-down attentional control. In contrast, imagery preferentially activated the left supplementary motor area and right opercular inferior frontal gyrus, implying a greater demand for internal representation and cognitive control. The imagery phase further demonstrated widespread activation across the frontoparietal network and temporal lobe, with image generation eliciting the strongest engagement of auditory and attentional regions. Self-reported vividness during imagery correlated positively with pre-scan vividness scores (p<0.05), validating the ecological relevance of the task. These findings suggest that while perception and imagery share a common neural foundation, they diverge in the specific cognitive processes they recruit, with imagery placing greater emphasis on internal generation and manipulation of mental representations. The study highlights the dynamic interplay of brain regions supporting visual imagery and its multifaceted nature, offering potential implications for interventions targeting cognitive enhancement and addressing deficits in perception or imagery.