The neural realm of taxonomic and thematic relation: an fMRI study

Taxonomic and thematic relations are part of an integrated memory system grounded in the sensory, perceptual and motor systems and distributed across important brain regions. Although essential for human communication and cognition, their neural basis is still a point of controversy. This study used neuroimaging to demonstrate the involvement of the frontal, parietal, occipital and temporal regions in comparison to the control (pseudo-word condition). Subjects underwent functional magnetic resonance imaging (fMRI) during an auditory semantic priming task involving decision-making about similarities of the presented word pairs based on taxonomic and thematic relations. The precise common region was identified as the ventral occipito-temporal cortex. Direct comparison across semantic conditions indicated that the inferior frontal, supramarginal gyrus, medial and anterior temporal poles were involved as key regions for taxonomic relations. Additional regions for thematic relations were not identified, thus implying the possibility of highly variable nature of taxonomic and thematic relation.