Flower, N. | Search bioRxiv

bioRxiv2025

A Unified Neural Timecourse for Words, Phrases, and Sentences: MEG Evidence from Parallel Presentation

Recent behavioral and neural research on reading shows that humans can extract syntactic structure from short sentences within a fraction of a second--faster than many estimates for recognizing the meaning of a single word. This challenges a core assumption of many language processing models: that combinatory operations depend on prior lexical access. Further, studies using parallel presentation of full sentences have revealed electrophysiological responses remarkably similar to those well established for single words. This raises the question of whether words, phrases, and sentences all move through the same processing stages, regardless of syntactic complexity. Using magnetoencephalography (MEG), we examined how single words, phrases, and sentences are processed when all visual information is available at once. Across all three levels, we observed highly similar waveform dynamics, with early responses reflecting bottom-up detection of form followed by activity in the left anterior and posterior temporal cortices and vmPFC consistent with combinatory processing. Of these regions, the left anterior temporal lobe (LATL) showed effects of bigram frequency suggestive of serial left-to-right dynamics. Together, these results support a Global-to-Serial Assembly (GLOSA) model in which the brain first detects the global form of the stimulus in a snapshot-like manner and then probes its combinatory properties through partially serial processes.

neuroscience↗

bioRxiv2024

The spatiotemporal dynamics of bottom-up and top-down processing during at-a-glance reading

Like all domains of cognition, language processing is affected by top-down knowledge. Classic evidence for this is missing blatant errors in the signal. In sentence comprehension, one instance of this is failing to notice word order errors, such as transposed words in the middle of a sentence: you that read wrong (Mirault et al., 2018). Our brains seem to fix such errors, since they are incompatible with our grammatical knowledge. But how do our brains do this? Following behavioral work on inner transpositions, we flashed four-word sentences for 300ms using rapid parallel visual presentation (RPVP, Snell and Grainger, 2017). We compared their magnetoencephalography responses to fully grammatical and reversed sentences. Left lateral language cortex robustly distinguished grammatical and reversed sentences starting at 213ms. Thus, the influence of grammatical knowledge begun rapidly after visual word form recognition (Tarkiainen et al., 1999). At the earliest stage of this neural "sentence superiority effect," inner transpositions patterned between grammatical and reversed sentences, showing evidence that the brain initially "noticed" the error. However, a hundred millisecond later, the inner transpositions became indistinguishable from the grammatical sentences, suggesting that at this point, the brain had "fixed" the error. These results show that after a single glance at a sentence, syntax impacts our neural activity almost as quickly as higher-level object recognition is assumed to take place (Cichy et al., 2014). The earliest stage involves a detailed comparison between the bottom-up input and grammatical knowledge, while shortly afterwards, knowledge can override an error in the stimulus.

neuroscience↗