Transient perturbation of the left temporal cortex evokes plasticity-related reconfiguration of the lexical network

Abstract

While much progress has been made in how brain organization supports language function, the language network's ability to adapt to immediate disturbances by means of reorganization remains unclear. The aim of this study was to examine acute reorganizational changes in brain activity related to conceptual and lexical retrieval in unimpaired language production following transient disruption of the left middle temporal gyrus (MTG). In a randomized single‐blind within‐subject experiment, we recorded the electroencephalogram from 16 healthy participants during a context‐driven picture‐naming task. Prior to the task, the left MTG was perturbed with real continuous theta‐burst stimulation (cTBS) or sham stimulation. During the task, participants read lead‐in sentences creating a constraining (e.g., “The farmer milks the”) or nonconstraining context (e.g., “The farmer buys the”). The last word was shown as a picture that participants had to name (e.g., “cow”). Replicating behavioral studies, participants were overall faster in naming pictures following a constraining relative to a nonconstraining context, but this effect did not differ between real and sham cTBS. In contrast, real cTBS increased overall error rates compared to sham cTBS. In line with previous studies, we observed a decrease in alpha‐beta (8–24 Hz) oscillatory power for constraining relative to nonconstraining contexts over left temporal–parietal cortex after participants received sham cTBS. However, following real cTBS, this decrease extended toward left prefrontal regions associated with both domain‐general and domain‐specific control mechanisms. Our findings provide evidence that immediately after perturbing the left MTG, the lexical‐semantic network is able to quickly reconfigure, also recruiting domain‐general regions.

Across‐session consistency of context‐driven language processing: A magnetoencephalography study

“…Therefore, healthy participants were tested with MEG while performing a context‐driven picture‐naming task, similar to sentence completion (Wilson et al., 2017). Replicating previous findings (Klaus et al., 2020; Piai et al, 2014, 2015, 2017, 2018, 2020) in both sessions, the behavioral differences demonstrated faster picture naming for constrained than unconstrained sentences, indicating that the context of constrained sentences provides the necessary information for enabling conceptual and lexical retrieval already prior to the target picture being shown. Also the MEG source level results were in accordance with these findings and revealed the expected power decreases in the alpha–beta frequency range in the left hemisphere.…”

“…We used the same sentence completion as picture‐naming paradigm (i.e., context‐driven picture naming) as previously employed in electrophysiological studies by our group (Klaus, Schutter, & Piai, 2020; Piai, Klaus, & Rossetto, 2020; Piai et al, 2017; Piai, Roelofs, & Maris, 2014; Piai, Roelofs, Rommers, & Maris, 2015; Piai, Rommers, & Knight, 2018). This paradigm has repeatedly elicited robust oscillatory power decreases in the alpha–beta range (8–25 Hz) prior to picture onset in healthy participants as well as stroke patients.…”