scholarly journals Verbal Fluency in Mild Alzheimer’s Disease: Transcranial Direct Current Stimulation over the Dorsolateral Prefrontal Cortex

2021 ◽  
pp. 1-11
Author(s):  
Daniela Smirni ◽  
Massimiliano Oliveri ◽  
Eliana Misuraca ◽  
Angela Catania ◽  
Laura Vernuccio ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Verbal Fluency ◽  
Dorsolateral Prefrontal Cortex ◽  
Control Group ◽  
Direct Current Stimulation ◽  
Cathodal Tdcs ◽  
Dorsolateral Prefrontal ◽  
The Right

Background: Recent studies showed that in healthy controls and in aphasic patients, inhibitory trains of repetitive transcranial magnetic stimulation (rTMS) over the right prefrontal cortex can improve phonemic fluency performance, while anodal transcranial direct current stimulation (tDCS) over the left prefrontal cortex can improve performance in naming and semantic fluency tasks. Objective: This study aimed at investigating the effects of cathodal tDCS over the left or the right dorsolateral prefrontal cortex (DLPFC) on verbal fluency tasks (VFT) in patients with mild Alzheimer’s disease (AD). Methods: Forty mild AD patients participated in the study (mean age 73.17±5.61 years). All participants underwent cognitive baseline tasks and a VFT twice. Twenty patients randomly received cathodal tDCS to the left or the right DLPFC, and twenty patients were assigned to a control group in which only the two measures of VFT were taken, without the administration of the tDCS. Results: A significant improvement of performance on the VFT in AD patients was present after tDCS over the right DLPFC (p = 0.001). Instead, no difference was detected between the two VFTs sessions after tDCS over the left DLPFC (p = 0.42). Furthermore, these results cannot be related to task learning effects, since no significant difference was found between the two VFT sessions in the control group (p = 0.73). Conclusion: These data suggest that tDCS over DLPFC can improve VFT performance in AD patients. A hypothesis is that tDCS enhances adaptive patterns of brain activity between functionally connected areas.

scholarly journals Efficiency of Repetitive Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex in Disorders of Consciousness: A Randomized Sham-Controlled Study

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Min Wu ◽  
Yamei Yu ◽  
Lunjie Luo ◽  
Yuehao Wu ◽  
Jian Gao ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Dorsolateral Prefrontal Cortex ◽  
Disorders Of Consciousness ◽  
Anodal Tdcs ◽  
Direct Current Stimulation ◽  
Dorsolateral Prefrontal ◽  
The Right ◽  
Stimulation Of

Conventional transcranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex (DLPFC) could improve arousal in disorders of consciousness (DOC). However, the comparative effectiveness of anodal stimulation of the left DLPFC and the electrophysiological effect of tDCS are yet to be determined. In this randomized sham-controlled design, patients were separated into three groups (left/right anodal tDCS, sham). Data on the clinical assessments and EEG were collected at baseline and after 2 weeks of tDCS. The outcome at 3-month follow-up was evaluated using the Glasgow Outcome Scale-Extended. Results showed that sessions of the left tDCS facilitated the excitability of the prefrontal cortex, whereas only one patient had a positive outcome. Targeting the right DLPFC was less effective, merely leading to activation of the stimulation site, with no effect on the state of arousal. Moreover, sham stimulation had minimal or no effect on any of the outcomes. These results provide evidence for a hemispheric asymmetry of tDCS effects in patients with DOC. Left anodal tDCS might be more effective for modulating cortical excitability compared to tDCS on the right DLPFC. However, future studies with large sample sizes are needed to confirm these findings. This trial is registered with NCT03809936.

scholarly journals Involvement of the Right Dorsolateral Prefrontal Cortex in Numerical Rule Induction: A Transcranial Direct Current Stimulation Study

2020 ◽  
Vol 14 ◽  
Author(s):  
Yuzhao Yao ◽  
Xiuqin Jia ◽  
Jun Luo ◽  
Feiyan Chen ◽  
Peipeng Liang
Keyword(s):  
Prefrontal Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Dorsolateral Prefrontal Cortex ◽  
Critical Role ◽  
Inductive Reasoning ◽  
Anodal Tdcs ◽  
Direct Current Stimulation ◽  
Dorsolateral Prefrontal ◽  
The Right

Numerical inductive reasoning has been considered as one of the most important higher cognitive functions of the human brain. Importantly, previous behavioral studies have consistently reported that one critical component of numerical inductive reasoning is checking, which often occurs when a discrepant element is discovered, and reprocessing is needed to determine whether the discrepancy is an error of the original series. However, less is known about the neural mechanism underlying the checking process. Given that the checking effect involves cognitive control processes, such as the incongruent resolution, that are linked to the right dorsolateral prefrontal cortex (DLPFC), this study hypothesizes that the right DLPFC may play a specific role in the checking process. To test the hypothesis, this study utilized the transcranial direct current stimulation (tDCS), a non-invasive brain stimulation method that could modulate cortical excitability, and examined whether and how the stimulation of the right DLPFC via tDCS could modulate the checking effect during a number-series completion problem task. Ninety healthy participants were allocated to one of the anodal, cathodal, and sham groups. Subjects were required to verify whether number sequences formed rule-based series, and checking effect was assessed by the difference in performance between invalid and valid conditions. It was found that significantly longer response times (RTs) were exhibited in invalid condition compared with valid condition in groups of anodal, cathodal, and sham tDCS. Furthermore, the anodal tDCS significantly shortened the checking effect than those of the cathodal and sham groups, whereas no significantly prolonged checking effect was detected in the cathodal group. The current findings indicated that anodal tDCS affected the process of checking, which suggested that the right DLPFC might play a critical role in the checking process of numerical inductive reasoning by inhibiting incongruent response.

Sign in / Sign up

Export Citation Format

Share Document