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Localizing component processes of picture naming using MEG recordings of covert picture-word interference and overt naming

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Poster C8 in Poster Session C, Wednesday, October 25, 10:15 am - 12:00 pm CEST, Espace Vieux-Port
This poster is part of the Sandbox Series.

Hsi T. Wei^1,2, Farhan B. Faisal², Tamara Beck², Claire Shao², Jed A. Meltzer^1,2; ¹Department of Psychology, University of Toronto, ²Rotman Research, Baycrest Hospital

Picture naming is a fundamental laboratory task for language production. Several variations of picture-naming tasks have been used to investigate behavioral and neurological factors underlying naming abilities. The picture-word interference (PWI) task is a crucial paradigm investigating the latency and brain activation related to the two main stages of word retrieval – semantic selection and phonological activation. In manipulating the semantic and phonological relations between distractor words and target pictures, the PWI task can create interference and facilitation at distinct stages of the naming process. However, despite the fast-paced nature of naming, relatively little research has been conducted with high temporal resolution recordings on PWI, compared to the rich literature on hemodynamic responses. Moreover, since vocal responses unavoidably create movement artifacts in all neuroimaging modalities, covert picture-naming designs without the need for vocal output are of high interest in the field. This preliminary study used magnetoencephalography (MEG) on three different covert and overt picture naming paradigms. The study aims to (1) further understand the MEG signals behind semantic interference and phonological facilitation induced by PWI, both locally and interhemispherically, and (2) compare brain activation patterns of covert and overt naming to examine the validity of covert naming tasks in measuring word retrieval processes. Aside from the traditional overt picture naming, we included two covert picture naming tasks. One was a covert PWI task where participants were instructed to ignore the audio distractor word and focus on judging whether the target picture name ends in a target sound assigned for the block by pressing yes/no buttons. The design of the covert PWI task was previously validated to elicit both semantic interference and phonological facilitation in a 4-experiment behavioural study on young healthy adults (Wei et al, 2022). The other covert naming task asked participants to judge whether the target picture name begins with the target sound assigned for the block by pressing yes/no buttons. The incentive for validating the beginning sound matching design was for the ease of future application on aphasic patients with difficulty understanding task instructions. Thirty young healthy adults (age: 22.73  4.36; 20 female) were recruited for the MEG study. With the exploratory nature of this study, we anticipate evoked and induced power modulations in the left temporal and frontal regions during semantic interference and phonological facilitation. Although most of the brain activations observed in previous literature using an overt design of PWI tend to be left lateralized, right hemisphere involvement has also been reported. Therefore, connectivity between the left and right homologous activation, if any, will be explored to reveal the potential transcallosal facilitation and/or inhibition during our covert PWI task. Furthermore, if covert naming can be validated for revealing processes of word retrieval, we expect to see comparable brain activation patterns during the covert naming paradigms with those of overt naming. If not, the differences between paradigms will be further explored and discussed.

Topic Areas: Language Therapy,