Abstract
We investigated the experiential bases of knowledge by asking whether people that perceive the world in a different way also show a different neurobiology of concepts. We characterized the brain activity of early-blind and sighted individuals during a conceptual retrieval task in which participants rated the similarity between color and action concepts. Between-categories analysis showed that, whereas multimodal concepts (action) activated a similar fronto-temporal network in the sighted and blind, color knowledge activated partially different brain regions in the two groups, with the posterior portion of the right IPS being significantly more active in the sighted compared to the blind. Interestingly, regions that were similarly activated in sighted and blind during conceptual processing (lpMTG for action, and precuneus for color), showed, however, an increased task-dependent connectivity with occipital regions in the blind. Finally, within-category adaptation analysis showed that word-pairs referring to perceptually similar color or actions led to repetition-suppression in occipital visual areas in the sighted only, whereas adaptation was observed in language-related temporal regions in the blind. Our results show that visual deprivation changes the neural bases of conceptual retrieval, which is partially grounded in sensorimotor experience.
Significance statement Do people with different sensory experience conceive the world differently? We tested whether conceptual knowledge builds on sensory experience by looking at the neurobiology of concepts in early blind individuals. We show that cortical regions involved in the processing of multimodal concepts (actions) are mostly similar in blind and sighted, whereas strictly visual concepts (colors) activated partially different brain topographies. Moreover, brain regions classically involved in conceptual retrieval showed different connectivity profiles in the blind, working in concert with re-organized “visual” areas. Finally, we further demonstrate that perceptual distance between concepts is represented in the visual cortex of the sighted, but not the blind. Blindness changes how the brain implements conceptual knowledge, which is partially grounded in sensorimotor experience.
