Representing words & concepts
We study the neuro-cognitive correlates of semantic knowledge (Borghesani & Piazza, Neuropsychologia, 2017). So far, we have seen how different concept features
- are encoded in distributed yet specialized cortical representations, with crucial topographical dissociations describing a posterior-to-anterior gradient from perceptual to conceptual features (Borghesani et al., Neuroimage, 2016)
- are automatically and rapidly retrieved when presented with symbolic information (Borghesani et al., JoCN, 2018)
- according to the task the subject is performing (Borghesani et al., JoCN, 2019)
Borghesani, V., Pedregosa, F., Buiatti, M., Amadon, A., Eger, E., & Piazza, M. (2016). Word meaning in the ventral visual path: a perceptual to conceptual gradient of semantic coding. NeuroImage, 143, 128-140.
In this fMRI experiment we tested the hypothesis that perceptual and conceptual dimensions of word meaning are coded in different brain regions: perceptual dimension in unimodal perceptual areas, conceptual dimension in heteromodal association areas. We tested the presence of a mapping between a perceptual dimension (implied real object size) and two conceptual dimensions (taxonomic categories at different levels of specificity), and the patterns of brain activity recorded in six areas along the ventral occipito–temporal cortical path. Combining multivariate pattern classification and representational similarity analysis, we found that the visual-perceptual dimension appears to be primarily encoded in early visual regions, while the conceptual dimension in more anterior temporal regions. This anteroposterior gradient of information content, from perceptual to conceptual, indicates that different areas along the ventral stream encode complementary dimensions of the semantic space.
Borghesani, V., Buiatti, M., Eger, E., & Piazza, M. (2018). Conceptual and Perceptual Dimensions of Word Meaning Are Recovered Rapidly and in Parallel during Reading. Journal of Cognitive Neuroscience, 1-14.
In this MEG experiment, we investigated whether perceptual and conceptual dimensions of word meaning are associated to different temporal dynamics. We compared one conceptual dimension (semantic category) and two perceptual dimensions (one concerning a visual feature - the implied real world size, and one concerning an auditory feature – prototypical sound). Our results indicate an automatic, rapid and essentially simultaneous recovery of information along both perceptual and conceptual dimensions of word meaning. However, the three different dimensions appear to dissociate in terms of the brain dynamics involved (changes in phase coherence vs spectral power) and the corresponding underlying sources.
Borghesani, V., Riello, M., Gesierich, B., Brentari, V., Monti, A., & Gorno-Tempini, M. (2019) The Neural Representations of Movement across Semantic Categories. Journal of Cognitive Neuroscience.
In this fMRI experiment, we compare three semantic categories (animals, tools, nontools) across two tasks (do they move in a similar way? vs. are they found in the same place?). Using both univariate and multivariate analyses we show that the same left fronto-parietal network is recruited to process movement properties of items (including both biological and non-biological motion ) regardless of their semantic category.