A Behavioral Manipulation Engages Right Frontal Cortex During Aphasia Therapy

Benjamin, Michelle; Towler, Stephen; Garcia, Amanda; Park, Hyejin; Sudhyadhom, Atchar; Harnish, Stacy M.; McGregor, Keith M.; Zlatar, Zvinka Z.; Reilly, Jamie; Rosenbek, John C.; Rothi, Leslie J. Gonzalez; Crosson, Bruce

doi:10.1177/1545968313517754

Cited by 35 publications

(39 citation statements)

References 24 publications

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“…A number of behavioral studies in healthy individuals and patients with aphasia have shown that pre-activation of the motor system can improve language production (Hanlon et al, 1990; Hadar et al, 1998; Holle and Gunter, 2007; Dick et al, 2009; Meinzer et al, 2011a; Benjamin et al, 2014). Moreover, inhibition of M1 by cathodal-tDCS resulted in reduced language learning (Liuzzi et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Transcranial direct current stimulation of the primary motor cortex improves word-retrieval in older adults

Meinzer

Lindenberg

Sieg

et al. 2014

Front. Aging Neurosci.

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Language facilitation by transcranial direct current stimulation (tDCS) in healthy individuals has generated hope that tDCS may also allow improving language impairment after stroke (aphasia). However, current stimulation protocols have yielded variable results and may require identification of residual language cortex using functional magnetic resonance imaging (fMRI), which complicates incorporation into clinical practice. Based on previous behavioral studies that demonstrated improved language processing by motor system pre-activation, the present study assessed whether tDCS administered to the primary motor cortex (M1) can enhance language functions. This proof-of-concept study employed a sham-tDCS controlled, cross-over, within-subject design and assessed the impact of unilateral excitatory (anodal) and bihemispheric (dual) tDCS in 18 healthy older adults during semantic word-retrieval and motor speech tasks. Simultaneous fMRI scrutinized the neural mechanisms underlying tDCS effects. Both active tDCS conditions significantly improved word-retrieval compared to sham-tDCS. The direct comparison of activity elicited by word-retrieval vs. motor-speech trials revealed bilateral frontal activity increases during both anodal- and dual-tDCS compared to sham-tDCS. This effect was driven by more pronounced deactivation of frontal regions during the motor-speech task, while activity during word-retrieval trials was unaffected by the stimulation. No effects were found in M1 and secondary motor regions. Our results show that tDCS administered to M1 can improve word-retrieval in healthy individuals, thereby providing a rationale to explore whether M1-tDCS may offer a novel approach to improve language functions in aphasia. Functional magnetic resonance imaging revealed neural facilitation specifically during motor speech trials, which may have reduced switching costs between the overlapping neural systems for lexical retrieval and speech processing, thereby resulting in improved performance.

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Section: Discussionmentioning

confidence: 99%

Transcranial direct current stimulation of the primary motor cortex improves word-retrieval in older adults

Meinzer

Lindenberg

Sieg

et al. 2014

Front. Aging Neurosci.

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“…For example, intention treatment, which uses a left-hand movement to initiate word finding efforts, increases right relative to left frontal activity, demonstrating reorganisation of word retrieval for picture naming and category member generation. 57 Simple practice in word retrieval without the hand movement does not produce this re-organisation. In the relatively fluent patients in this study, the impact of this manipulation on right posterior perisylvian activity correlated with treatment gains.…”

Section: Non-language Behaviours For Therapeutic Neuromodulationmentioning

confidence: 98%

Neuroplasticity and aphasia treatments: new approaches for an old problem

Crosson

Rodriguez

Copland

et al. 2019

J Neurol Neurosurg Psychiatry

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Given the profound impact of language impairment after stroke (aphasia), neuroplasticity research is garnering considerable attention as means for eventually improving aphasia treatments and how they are delivered. Functional and structural neuroimaging studies indicate that aphasia treatments can recruit both residual and new neural mechanisms to improve language function and that neuroimaging modalities may hold promise in predicting treatment outcome. In relatively small clinical trials, both non-invasive brain stimulation and behavioural manipulations targeting activation or suppression of specific cortices can improve aphasia treatment outcomes. Recent language interventions that employ principles consistent with inducing neuroplasticity also are showing improved performance for both trained and novel items and contexts. While knowledge is rapidly accumulating, larger trials emphasising how to select optimal paradigms for individualised aphasia treatment are needed. Finally, a model of how to incorporate the growing knowledge into clinical practice could help to focus future research.

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“…Rather, we administered anodal tDCS in both active conditions to the left primary motor cortex. Behaviorally, preactivation of the motor network by behavioral interventions or anodal tDCS resulted in improved language processing in healthy individuals and patients with poststroke language impairment (e.g., Meinzer et al, 2016;Benjamin et al, 2014;Meinzer, Lindenberg, Sieg, et al, 2014;Hadar, Wenkert-Olenik, Krauss, & Soroker, 1998). Moreover, inhibitory cathodal M1-tDCS has been shown to interfere with language processing (Liuzzi et al, 2008).…”

Section: Baseline Neural Network Organization and Impact On Tdcs Effectsmentioning

confidence: 99%

Effects of Transcranial Direct Current Stimulation on Neural Networks in Young and Older Adults

Martin

Meinzer

Lindenberg

et al. 2017

Journal of Cognitive Neuroscience

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Transcranial direct current stimulation (tDCS) may be a viable tool to improve motor and cognitive function in advanced age. However, although a number of studies have demonstrated improved cognitive performance in older adults, other studies have failed to show restorative effects. The neural effects of beneficial stimulation response in both age groups is lacking. In the current study, tDCS was administered during simultaneous fMRI in 42 healthy young and older participants. Semantic word generation and motor speech baseline tasks were used to investigate behavioral and neural effects of uni- and bihemispheric motor cortex tDCS in a three-way, crossover, sham tDCS controlled design. Independent components analysis assessed differences in task-related activity between the two age groups and tDCS effects at the network level. We also explored whether laterality of language network organization was effected by tDCS. Behaviorally, both active tDCS conditions significantly improved semantic word retrieval performance in young and older adults and were comparable between groups and stimulation conditions. Network-level tDCS effects were identified in the ventral and dorsal anterior cingulate networks in the combined sample during semantic fluency and motor speech tasks. In addition, a shift toward enhanced left laterality was identified in the older adults for both active stimulation conditions. Thus, tDCS results in common network-level modulations and behavioral improvements for both age groups, with an additional effect of increasing left laterality in older adults.

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A Behavioral Manipulation Engages Right Frontal Cortex During Aphasia Therapy

Cited by 35 publications

References 24 publications

Transcranial direct current stimulation of the primary motor cortex improves word-retrieval in older adults

Transcranial direct current stimulation of the primary motor cortex improves word-retrieval in older adults

Neuroplasticity and aphasia treatments: new approaches for an old problem

Effects of Transcranial Direct Current Stimulation on Neural Networks in Young and Older Adults

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