Left parietal cortex transcranial direct current stimulation enhances gesture processing in corticobasal syndrome

The representation and processing of numerosity is a crucial cognitive capacity. Converging evidence points to the posterior parietal cortex (PPC) as primary “number” region. However, the exact role of the left and right PPC for different types of numerical and arithmetic tasks remains controversial. In this study, we used high-definition transcranial direct current stimulation (HD-tDCS) to further investigate the causal involvement of the PPC during approximative, nonsymbolic mental arithmetic. Eighteen healthy participants received three sessions of anodal HD-tDCS at 1-week intervals in counterbalanced order: left PPC, right PPC, and sham stimulation. Results showed an improved performance during online parietal HD-tDCS (vs. sham) for subtraction problems. Specifically, the general tendency to underestimate the results of subtraction problems (i.e., the “operational momentum effect”) was reduced during online parietal HD-tDCS. There was no difference between left and right stimulation. This study thus provides new evidence for a causal involvement of the left and right PPC for approximate nonsymbolic arithmetic and advances the promising use of noninvasive brain stimulation in increasing cognitive functions.

Download Full-text

Power spectral parameter variations after transcranial direct current stimulation in a bimanual coordination task

Adaptive Behavior ◽

10.1177/1059712319879971 ◽

2019 ◽

pp. 105971231987997 ◽

Cited By ~ 1

Author(s):

Atefeh Azarpaikan ◽

HamidReza Taherii Torbati ◽

Mehdi Sohrabi ◽

Reza Boostani ◽

Majid Ghoshuni

Keyword(s):

Parietal Cortex ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Bimanual Coordination ◽

Neuronal Membrane ◽

Membrane Excitability ◽

Direct Current Stimulation ◽

Cerebellar Tdcs ◽

Alpha Beta ◽

The Brain

Transcranial direct current stimulation (tDCS) can shift neuronal membrane excitability by applying a weak slow electric current to the brain through the scalp. Attendant electroencephalography (EEG) can provide valuable information about the tDCS mechanisms. This study investigated the effects of anodal tDCS on parietal cortex and cerebellum activity to reveal possible modulation of spontaneous oscillatory brain activity. Timing of the tDCS priming protocol in relation to the intervention especially with respect to bimanual coordination task was also studied. EEG activity was measured in 120 healthy participants before and after sessions of anodal stimulation of the parietal cortex and cerebellum to detect the tDCS-induced alterations. Variations of the delta, theta, alpha, beta, and sensorimotor rhythm (SMR) power bands were analyzed using a MATLAB program. The results showed that anodal parietal and cerebellar tDCS cause changes in brain wave frequencies. They also showed an increase in alpha, beta, and SMR power bands during stimulation sessions for during stimulation parietal group ( p ≤ .01). Also, theta, alpha, beta, and SMR power bands were increased in during stimulation cerebellum group in stimulation sessions and 48 h later ( p ≤ .01). Moreover, the results revealed that the tDCS intervention led to a variety of activations in some areas of the brain. Altogether, the cerebellar tDCS during motor task had a significant improvement in off-line learning.

Download Full-text