Falagiarda, F. | Search bioRxiv

bioRxiv2024

Widespread neural reorganization related to expertise in reading visual Braille

Learning to read assigns linguistic value to an abstract visual code. Whether regions of the reading network tune to visual properties common to most scripts or code for more abstracted units of language remains debated. Here we investigate this question using visual Braille, a script developed for touch that does not share the typical explicit shape information of other alphabets, yet maps onto the same phonology and lexicon as other more regular scripts. First, we compared univariate responses in visual Braille readers and a naive control group and found that individually localized Visual Word Form Area (VWFA) was selectively activated for visual Braille when compared to scrambled Braille only in expert Braille readers. Multivariate analyses showed that linguistic properties can be decoded from Latin script in both groups and from Braille script in expert readers in an extended network of brain regions including the early visual cortex (V1), the lateral occipital region (LO), the VWFA and the left Posterior Temporal area (l-PosTemp). These results suggest that the tuning of an extended reading network to orthography relies more on the linguistic content of the script rather than their specific visual features (e.g. line junctions). Nevertheless, cross-scripts generalization was significantly lower than within-script decoding and failed to reveal common representations across Latin and Braille in experts in all regions except the l-PosTemp. These results suggest that V1, LO and VWFA encode orthographic representations in a script-specific manner, whereas l-PosTemp encodes abstracted linguistic information.

neuroscience↗

bioRxiv2023

Vision plays a calibrating role in discriminating threat-related vocal emotions

The ability to reliably discriminate vocal expressions of emotion is crucial to engage in successful social interactions. This process is arguably more crucial for blind individuals, since they cannot extract social information from faces and bodies, and therefore chiefly rely on voices to infer the emotional state of their interlocutors. Blind have demonstrated superior abilities in several aspects of auditory perception, but research on their ability to discriminate vocal features is still scarce and has provided unclear results. Here, we used a gating psychophysical paradigm to test whether early blind people would differ from individually matched sighted controls at the recognition of emotional expressions. Surprisingly, blind people showed lower performance than controls in discriminating specific vocal emotions. We presented segments of non-linguistic emotional vocalizations of increasing duration (100 to 400ms), portraying five basic emotions (fear, happy, sad, disgust, angry), and we asked our participants for an explicit emotion categorization task. We then calculated sensitivity indices and confusion patterns of their performance. We observed better performance of the sighted group in the discrimination of angry and fearful expression, with no between-group differences for other emotions. This result supports the view that vision plays a calibrating role for specific threat-related emotions specifically.

neuroscience↗