Randomized, crossover, sham-controlled, double-blind study of transcranial direct current stimulation of left DLPFC on executive functions

2018 ◽  
Vol 36 (6) ◽  
pp. 755-766 ◽  
Author(s):  
Laurence Dumont ◽  
Sofia El Mouderrib ◽  
Hugo Théoret
Keyword(s):  
Executive Functions ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Blind Study ◽  
Double Blind Study ◽  
Double Blind ◽  
Direct Current Stimulation ◽  
Left Dlpfc ◽  
Stimulation Of

Impact of Combined Transcranial Direct Current Stimulation and Speech-language Therapy on Spontaneous Speech in Aphasia: A Randomized Controlled Double-blind Study

2020 ◽  
Vol 26 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Elodie Guillouët ◽  
Mélanie Cogné ◽  
Elisabeth Saverot ◽  
Nicolas Roche ◽  
Pascale Pradat-Diehl ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Outcome Measure ◽  
Spontaneous Speech ◽  
Blind Study ◽  
Double Blind Study ◽  
Language Therapy ◽  
Double Blind ◽  
Main Outcome Measure ◽  
Direct Current Stimulation

AbstractObjective:Aphasia recovery depends on neural reorganization, which can be enhanced by speech-language therapy and noninvasive brain stimulation. Several studies suggested that transcranial direct current stimulation (tDCS) associated with speech-language therapy may improve verbal performance evaluated by analytic tests, but none focused on spontaneous speech. We explored the effect of bihemispheric tDCS on spontaneous speech in patients with poststroke aphasia.Methods:In this multicentric controlled randomized cross-over double-blind study, we included 10 patients with poststroke aphasia (4 had aphasia >6 months and 6 with aphasia <6 months). We combined the sessions of speech-language therapy and bihemispheric tDCS (2 mA, 20 min). After three baseline speech evaluations (1/week), two different conditions were randomly consecutively proposed: active and sham tDCS over 3 weeks with 1 week of washout in between. The main outcome measure was the number of different nouns used in 2 min to answer the question “what is your job.”Results:There was no significant difference between conditions concerning the main outcome measure (p = .47) nor in the number of verbs, adjectives, adverbs, pronouns, repetitions, blank ideas, ideas, utterances with grammatical errors or paraphasias used. Other cognitive functions (verbal working memory, neglect, or verbal fluency) were not significantly improved in the tDCS group. No adverse events occurred.Conclusion:Our results differed from previous studies using tDCS to improve naming in patients with poststroke aphasia possibly due to bihemispheric stimulation, rarely used previously. The duration of the rehabilitation period was short given the linguistic complexity of the measure. This negative result should be confirmed by larger studies with ecological measures.

scholarly journals Transcranial direct current stimulation above the medial prefrontal cortex counteracts the effects of diminished outcome controllability during reinforcement learning

2020 ◽  
Author(s):  
Gábor Csifcsák ◽  
Jorunn Bjørkøy ◽  
Sarjo Kuyateh ◽  
Haakon Reithe ◽  
Matthias Mittner
Keyword(s):  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Direct Current ◽  
Learned Helplessness ◽  
Transcranial Direct Current Stimulation ◽  
Parameter Estimates ◽  
Double Blind Study ◽  
High Definition ◽  
Double Blind ◽  
Direct Current Stimulation

Background: The arbitration between decision-making strategies is shaped by the degree of controllability over environmental events. Under low control, individuals might rely more heavily on Pavlovian bias (PB), which facilitates and inhibits actions when facing appetitive and aversive cues, respectively. More recently, extreme PB was implicated in learned helplessness (LH), which is typically induced by uncontrollable punishment. On the neural level, the medial prefrontal cortex (mPFC) was pinpointed as a region underlying both cognitive control over PB, and the pathogenesis of LH.Objective/Hypothesis: To test if high-definition transcranial direct current stimulation (HD-tDCS) targeting the mPFC counteracts with the deleterious behavioral effects of low controllability over rewards/losses (“yoking”) during reinforcement learning.Methods: In a pre-registered, between-group, double-blind study (N = 103, healthy adults), we tested the interaction of low controllability and HD-tDCS on performance in a Go/NoGo task. Yoking was implemented by presenting random outcomes following responses, while matching reward/loss frequencies between control and yoked groups. HD-tDCS was delivered for 15 minutes at 2 mA using a 4x1 montage centered at position Fz.Results: HD-tDCS improved response accuracy by the end of the task only when applied simultaneously with yoking. The beneficial consequences of active stimulation in yoked participants were more pronounced in reward-predictive trials. Finally, computational modeling revealed that parameter estimates of learning rate and choice randomness were modulated by yoking and HD-tDCS in an interactive manner.Conclusions: These results highlight the potential of our HD-tDCS protocol for interfering with choice arbitration in volatile environments, resulting in more adaptive behavior.

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