Testing the dorsal and ventral pathways in reading : a tDCS study

• Main Author: Cheng Wenxuan
• Other Authors: Annabel Chen Shen-Hsing
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Social sciences::Psychology
• Online Access: https://hdl.handle.net/10356/148392
• Institution: Nanyang Technological University

Reading aloud involves the conversion of visual input of words to pronunciations. Previous research has long established a model for reading aloud with two processing routes: (a) the sub-lexical route for graphophonological processing, which accounts for pseudoword reading; and (b) the lexical route for semantic processing, which accounts for irregular word reading. Neuroimaging evidence supported a dorsal pathway for sub-lexical processing and a ventral pathway for lexical processing in the reading network, but few tested the relationship using transcranial direct current stimulation (tDCS). Here, we examined how dorsal stimulation (anode at CP5 and cathode at Cz) and ventral stimulation (anode at TP7 and cathode at the nape of the neck) modulate word reading proficiency of regular words, irregular words and pseudowords. 15 participants with high English proficiency participated in three 20min sessions of sham, dorsal, and ventral stimulation respectively, each followed by a word reading task consisting of the three word types. While regular word reading efficiency was improved by ventral stimulation, it was worsened by dorsal stimulation. Both stimulations failed to modulate irregular word and pseudoword reading. In addition, a gender difference was found in tDCS modulation such that males experienced greater effects and females drove the negative effects. This study adds evidence to the research on tDCS modulation of reading in the healthy population, where results are often mixed and insignificant. The need to examine lexical/sub-lexical processing proficiency and gender difference in future tDCS studies on reading is highlighted.