The effects of bilateral posterior parietal cortex tRNS on reading performance

• Published in: Cerebral cortex (New York, N.Y. 1991) Vol. 33; no. 9; pp. 5538 - 5546
• Main Authors: Bertoni, Sara, Franceschini, Sandro, Campana, Gianluca, Facoetti, Andrea
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 25.04.2023
• Subjects: Brain Mapping - methods; Humans; Magnetic Resonance Imaging - methods; Parietal Lobe - physiology; Reading; Young Adult; visual word form area; multisensory attention; dorsal visual pathway; reading neural networks; noninvasive brain stimulation
• ISSN: 1047-3211; 1460-2199; 1460-2199
• DOI: 10.1093/cercor/bhac440

Abstract According to established cognitive neuroscience knowledge based on studies on disabled and typically developing readers, reading is based on a dual-stream model in which a phonological-dorsal stream (left temporo-parietal and inferior frontal areas) processes unfamiliar words and pseudowords, whereas an orthographic-ventral stream (left occipito-temporal and inferior frontal areas) processes known words. However, correlational neuroimaging, causal longitudinal, training, and pharmacological studies have suggested the critical role of visuo-spatial attention in reading development. In a double blind, crossover within-subjects experiment, we manipulated the neuromodulatory effect of a short-term bilateral stimulation of posterior parietal cortex (PPC) by using active and sham tRNS during reading tasks in a large sample of young adults. In contrast to the dual-stream model predicting either no effect or a selective effect on the stimulated phonological-dorsal stream (as well as to a general multisensory effect on both reading streams), we found that only word-reading performance improved after active bilateral PPC tRNS. These findings demonstrate a direct neural connectivity between the PPC, controlling visuo-spatial attention, and the ventral stream for visual word recognition. These results support a neurobiological model of reading where performance of the orthographic-ventral stream is boosted by an efficient deployment of visuo-spatial attention from bilateral PPC stimulation.