Parallel or sequential? Decoding conceptual and phonological/phonetic information from MEG signals during language production

ABSTRACT

Speaking requires the temporally coordinated planning of core linguistic information, from conceptual meaning to articulation. Recent neurophysiological results suggested that these operations involve a cascade of neural events with subsequent onset times, whilst competing evidence suggests early parallel neural activation. To test these hypotheses, we examined the sources of neuromagnetic activity recorded from 34 participants overtly naming 134 images from 4 object categories (animals, tools, foods and clothes). Within each category, word length and phonological neighbourhood density were co-varied to target phonological/phonetic processes. Multivariate pattern analyses (MVPA) searchlights in source space decoded object categories in occipitotemporal and middle temporal cortex, and phonological/phonetic variables in left inferior frontal (BA 44) and motor cortex early on. The findings suggest early activation of multiple variables due to intercorrelated properties and interactivity of processing, thus raising important questions about the representational properties of target words during the preparatory time enabling overt speaking.

KEYWORDS:

• Conceptual preparation
• phonological encoding
• cascading vs. parallel processes
• magnetoencephalography
• pattern classification

Acknowledgements

We thank Peter Hagoort, the Neurobiology of Language Department of the MPI and DCCN, and Vitoria Piai for insightful discussions at earlier stages of our study. We are also thankful to Brad Mahon, Kristof Strijkers, and other two anonymous reviewers for their valuable comments and feedback on a previous version of the present article.

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Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.