Language and Memory Improvements following tDCS of Left Lateral Prefrontal Cortex

Abstract

Recent research demonstrates that performance on executive-control measures can be enhanced through brain stimulation of lateral prefrontal regions. Separate psycholinguistic work emphasizes the importance of left lateral prefrontal cortex executive-control resources during sentence processing, especially when readers must override early, incorrect interpretations when faced with temporary ambiguity. Using transcranial direct current stimulation, we tested whether stimulation of left lateral prefrontal cortex had discriminate effects on language and memory conditions that rely on executive-control (versus cases with minimal executive-control demands, even in the face of task difficulty). Participants were randomly assigned to receive Anodal, Cathodal, or Sham stimulation of left lateral prefrontal cortex while they (1) processed ambiguous and unambiguous sentences in a word-by-word self-paced reading task and (2) performed an n-back memory task that, on some trials, contained interference lure items reputed to require executive-control. Across both tasks, we parametrically manipulated executive-control demands and task difficulty. Our results revealed that the Anodal group outperformed the remaining groups on (1) the sentence processing conditions requiring executive-control, and (2) only the most complex n-back conditions, regardless of executive-control demands. Together, these findings add to the mounting evidence for the selective causal role of left lateral prefrontal cortex for executive-control tasks in the language domain. Moreover, we provide the first evidence suggesting that brain stimulation is a promising method to mitigate processing demands encountered during online sentence processing.

Effects of transcranial direct current stimulation on the working memory of post-stroke people: an integrative review

“…It is known that after stroke may occur a change in synaptic homeostasis, which affects individuals' cognition (21) . In the present study the verbal and visual WM showed significant improvements after the use of tDCS, supporting the results found in diverse population by other authors (22,23) . One possible explanation is that the modulation of membrane action potencial induced by tDCS could limit this homeostasis lost, therefore mantaining the cognitive functions (24) .…”

A common neural hub resolves syntactic and non-syntactic conflict through cooperation with task-specific networks

“…And, as sketched earlier, neuroimaging findings show co-localization of activity within the LIFG when the same subjects perform a canonical cognitive control task (Stroop, Flanker) and a sentence-processing task involving syntactic conflict (January et al, 2009; van de Meerendonk et al, 2013; Ye & Zhou, 2009). These correlational findings have been bolstered by recent work demonstrating a causal connection between cognitive control procedures and language processing: extensive practice on a cognitive control tasks leads to improved garden-path recovery (Hussey et al, 2016; Novick, Hussey, Teubner-Rhodes, Harbison, & Bunting, 2014); transcranial direct current stimulation of VLPFC mitigates the effects of syntactic ambiguity during real-time processing (Hussey, Ward, Christianson, & Kramer, 2015); and dynamic cognitive control engagement immediately facilitates recovery from misinterpretation during online comprehension (Hsu & Novick, 2016). …”

When Structure Competes with Semantics: Reading Chinese Relative Clauses

“…Adjudication between the resulting semantic representations, including full inhibition of one of the representations if required by the task at hand, requires time and effort (cf. Hussey et al, 2015)."Good-enough" processing is usually quite effective and accurate in normal linguistic environments; however, when materials are constructed to contain temporary ambiguities or to pit structure and semantics against one another (as is the case here), comprehension errors are frequently observed. Importantly for the present study, previous results within the good-enough framework predict the following interaction of structural difficulty and plausibility.…”

“…Evidence suggests that misinterpretations are derived from competition between the syntactic structure of the verbatim input and other information sources, i.e., various processing heuristics that can, under certain circumstances, overwhelm the syntactic structure (e.g., Christianson et al, 2001Christianson et al, , 2010Christianson & Luke, 2011;Christianson, Williams, Zacks, & Ferreira, 2006;Ferreira, 2003;den Ouden, Dickey, Anderson, & Christianson, 2016;Ferreira, Bailey, & Ferraro, 2002;Hussey, Ward, Christianson, & Kramer, 2015).…”

“…Adjudication between the resulting semantic representations, including full inhibition of one of the representations if required by the task at hand, requires time and effort (cf. Hussey et al, 2015).…”