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Object color knowledge representation in the brain of color-blind: Effects of language and sensory experiences
Poster A18 in Poster Session A, Tuesday, October 24, 10:15 am - 12:00 pm CEST, Espace Vieux-Port
Jiahui Lu1, Xiaoying Wang1, Yanchao Bi1,2; 1Beijing Normal University, 2Chinese Institute for Brain Research
Recent studies have identified different neural structures supporting knowledge representation derived from sensory and from language experiences (see review in Bi, 2021). Our previous work showed that object color knowledge is represented in both posterior fusiform gyrus that relies on visual color experiences (observed in only sighted individuals) and dorsal anterior lobe that is independent from visual experience (in both congenitally blind and sighted). However, how these two types of knowledge representation potentially modulate each other is poorly understood. To address this question, the current study investigated the object color knowledge neural representation in dichromats, whose visual-based and language-based color experience are mismatched due to their abnormal color perception (Saysani et al., 2018). We recruited 14 dichromats (DT; red/green color-blind) and 21 trichromats (TC) and tested their color knowledge on 14 color-diagnostic fruits and vegetables in both behavioral and fMRI tasks. Object color representational similarity matrices (RSM) were constructed through multi-arrangement tasks (arranging objects based on color similarity) with scrambled naturally colored object pictures (scrambled-picture color RSM) and object names (object name color RSM). In TC group the two RSMs were highly correlated (r = 0.81); In DT group, the correlation (r = 0.46) was significantly lower than the TC group (p < 0.05), indicating a dissociation between visual-based and language-based object color representation in the DT group. In the fMRI experiment the subjects were presented grayscale picture of these fruit and vegetables and asked to perform one-back real-world color similarity judgement task. In the color perception mask and the language mask, brain regions representing color knowledge matrices based on visual and language experience were similarly identified using representational similarity analysis (Kriegeskorte et al., 2008) in TC group, after controlling for the confounding effect of other object attributes (i.e., shape, touch, taste, semantic, size, texture). In these object color knowledge processing areas identified in the TC group, we tested whether the DT group represent object color based on visual experience (i.e., scrambled-picture color RSM) or based on language experience (object name color RSM) by performing RSA with each of these RSMs with the other one controlled for. In the bilateral fusiform/lingual gyrus (within the color perception mask), DT’s neural activity to gray-scale object pictures was significantly, specifically correlated with the object-name-color RSM (i.e., based on language experience; Bayesian one-sample t test: BF10 >= 2.01), reflecting the dominant role of language on the sensory-derived representation. In the left anterior temporal lobe (within the language mask), effects of both RSMs were significant, reflecting interaction between two systems. Whole brain searchlight RSA examining the interaction effect between behavior matrix (sensory vs language) and group (DT vs TC) further confirmed that the modulating effects of language on the object color knowledge representation in the color perception regions in the DT group. These results supported the neural dual coding of conceptual knowledge, and highlighted the potential interactions between these two types of representations.
Topic Areas: Meaning: Lexical Semantics,