The anterior temporal lobe (ATL) is suggested as a semantic hub that may support reading inconsistent words via semantic access. Surface alexia is characterized by difficulty in reading these inconsistent words, and often co-occurs with ATL atrophy and semantic impairments. However, the role of ATL in word reading is unclear, as evidenced by cases of alexia without semantic impairments and semantic impairments without surface alexia. To test its role in reading, we stimulated the ATL using transcranial Direct Current Stimulation in neurotypical participants performing a Word Naming task including consistent and inconsistent words, and a Picture Plausibility (PP) task involving nonverbal semantic judgments. We also stimulated the left tempo-occipital cortex (TOC) during the PP task. Low-frequency inconsistent words were read more slowly than high-frequency inconsistent words in the sham condition. This interaction disappeared with ATL stimulation. We found an interaction between consistency and stimulation in the low-frequency subset, but not in the high-frequency subset. In the PP task, ATL stimulation had no effect, whereas TOC stimulation significantly influenced reaction time. These findings support the left ATL's role in reading inconsistent words, aligning with surface alexia with ATL atrophy. The results also suggest that the left lateral ATL may be involved in lexical rather than purely semantic processes, consistent with lesion studies demonstrating a dissociation between semantic impairments and surface alexia, and possibly also with graded modality-specific specialization of bilateral ATLs. These findings reconcile conflicting findings and elucidate the role of left lateral ATL in reading.
Lexical access to common words is remarkably robust to changes in surface format (e.g., font, case, color, size), supporting abstractionist models in which orthographic codes are largely invariant to perceptual details. However, recent behavioral experiments have shown that brand names, a type of lexical item that is typically encountered in a highly consistent visual format, are sensitive to modifications of surface format (Labusch, Duñabeitia, & Perea, 2024; Perea et al., 2022). This research has largely focused on behavioral measures, leaving open questions about the neural mechanisms underlying brand name recognition. Here, we used fMRI to examine whether the visual word form area (VWFA) and related regions are sensitive to font and letter case modifications in brand names in a semantic categorization task (brand related to transportation or not). Participants viewed brand names presented either in their typical visual format, or with a modified font or case. Font modifications slowed responses and elicited increased VWFA activation relative to intact logos, whereas case modifications also slowed responses but did not reliably modulate activity in the canonical VWFA ROI. This dissociation constrains strong claims of strict format invariance in the VWFA, while remaining compatible with hierarchical or interactive accounts in which some ventral occipitotemporal populations retain sensitivity to learned surface forms. Rather than supporting a categorical claim of case invariance, the present data indicate stronger sensitivity to font than to letter case when a perceptual format is consistently tied to lexical identity.
Language, as a uniquely human faculty, combines words into hierarchical phrases with diverse syntactic-semantic relations (e.g., subject-predicate and modifier-head phrases). These phrase types are theoretically generated through the labeling algorithm at the syntax-semantics interface. Nevertheless, previous research has focused predominantly on the syntactic system, whereas the neural basis and temporal dynamics of labeling remain poorly understood. To address this gap, we developed the Head-Anchored Labeling Manipulation approach. This method manipulates labeling by embedding the same Mandarin noun-verb dual-category words as heads in tightly controlled modifier-head constructions, where the head alone determines the phrase's grammatical type. The representational similarity analysis of EEG data revealed that labeling representations emerged during both the early and middle stages: 192-227, 290-318, 330-360, and 385-416 ms following the dual-category word. Labeling emerged as early as ~200 ms, concurrent with syntactic Merge, and continued into the N400 window. These results demonstrate that labeling dynamically links syntax to conceptual-intentional system and generates phrase types by determining the constituent head. Its early engagement challenges syntax-first models and supports parallel interactive accounts. Moreover, combinability representations (520-596 and 604-632 ms), together with a late event-related brain potential negativity (420-700 ms) elicited by the dual-category word in the baseline condition, reflect increased difficulty in reconciling semantic associations with atypical syntactic configurations. Together, these findings provide clear electrophysiological evidence for the temporal dynamics of labeling and elucidate the processes at the syntax-semantics interface.
The non-selective processing hypothesis for bilinguals posits that during the processing of the target language, the lexical information of the non-target language is concurrently activated. Nonetheless, the lexical representation of bilinguals in both languages and the temporal dynamics of lexical information representation remain unclear. Here, we utilized fMRI in Experiment 1 and EEG in Experiment 2, combined with representational similarity analysis (RSA), to explore the neural representation of lexical access in both the target and non-target languages during L2 word reading and the modulatory effects of processing demands. Results of two Experiments jointly revealed that the lexical information of L2 was represented widely and earlier during L2 lexical processing, whereas the lexical information of L1 was represented widely and earlier during L2 semantic processing. These findings provide spatiotemporally integrated evidence for the bilingual non-selective access hypothesis, indicating that non-selective processing occurs only under conditions of high semantic processing demands.
Writing systems are cultural inventions that differ in how they represent spoken language. We tested how the brain learns to map arbitrary visual symbols to sound and meaning by comparing neural activity for artificial writing systems that were either alphabetic (systematic symbol-sound mappings) or logographic (arbitrary symbol-sound mappings). Twenty-four adults learned to read aloud and comprehend novel words written in each system. After 2 weeks of training, functional magnetic resonance imaging during reading comprehension revealed that the dorsal pathway (inferior parietal gyrus, inferior frontal gyrus), which is involved in mapping from print-to-sound, was more active for the alphabetic system, whereas the ventral pathway (anterior fusiform gyrus, middle temporal gyrus), which is involved in mapping from print-to-meaning, was more active for the logographic system. Combined with performance differences, these findings indicate that systematic symbol-sound mappings allowed the brain to bridge the interface between vision and meaning via sound, whereas an absence of systematicity made it more efficient to link vision directly to meaning. Thus, the same brain finds different solutions to the problem of reading that capitalise on the statistical properties of culturally invented writing systems.
