Decoding category and familiarity information during visual imagery.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Visual imagery involves a broad network of brain regions, overlapping with those active during sensory perception.
• Category-selective areas (e.g., FFA for faces, PPA for places) and semantic networks (precuneus, TPJ, mPFC, PCC) are implicated in perceiving familiar faces and places.

Purpose of the Study:

• To investigate the extent to which visual imagery network, category-selective, and semantic brain regions encode information about the category and familiarity of imagined stimuli.
• To determine if posterior visual areas and extended semantic networks contain representations of imagined stimuli categories and familiarity.

Main Methods:

• Utilized multivariate pattern analysis (MVPA) on fMRI data.
• Employed region-of-interest (ROI)-based MVPA to analyze data from visual imagery network nodes (V1, SPL, aIPS), category-selective regions (FFA, PPA), and extended semantic network areas.
• Participants imagined personally familiar and unfamiliar faces and places based on auditory cues.

Main Results:

• Distinguished between imagined faces and places within visual imagery network nodes (V1, SPL, aIPS), category-selective regions (FFA, PPA), and the extended semantic network (precuneus, mPFC, IFG, TPJ).
• Successfully decoded the familiarity of imagined stimuli in SPL, aIPS, and parts of the extended semantic network (right precuneus, right TPJ).
• V1, a posterior visual area, did not decode stimulus familiarity but contained categorical representations.

Conclusions:

• Posterior visual areas, including V1, contain categorical representations of imagined stimuli.
• Stimulus familiarity during visual imagery may be processed similarly to perception, engaging shared neural mechanisms.
• Findings suggest a significant overlap in neural representations for visual perception and imagery, particularly concerning stimulus category and familiarity.