Transcranial Electric Stimulation

This study is to find out whether and how a type of non-invasive electrical brain stimulation called transcranial electrical stimulation with temporal interference (TES-TI) can temporarily change brain activity in healthy adults. A structural MRI scan will be used to customize where the stimulation electrodes are placed for each participant to deliver TES-TI during three afternoon sessions at rest with eyes closed. Brain activity is recorded with high-density EEG. Up to 24 participants will be enrolled and on study for 3 to 12 weeks.

The goal of this randomised controlled trial is to investigate the effects of a 2-week high-frequency transcranial pulsed current stimulation (tPCS) on cognitive outcomes in older and healthy adults. The main questions it aims to answer are: 1. Would a single session of anodal tPCS over the left prefrontal cortex improve working memory, task inhibition, and task switching in healthy young and older adults, compared to anodal transcranial direct current stimulation (tDCS) and sham-tPCS? 2. Would repeated session of anodal-tPCS (2-weeks) lead to improvements in working memory, task inhibition, and task switching in healthy young and older adults, compared to tDCS and sham-tPCS? 3. Will tPCS be better tolerated among healthy adults, compared to tDCS? Researchers will compare tPCS / tDCS / sham-tPCS to see if there are any differences in cognitive outcomes after 1 session and after repeated sessions, as well as to compare the tolerance of tPCS against tDCS and sham-tPCS. Participants will be requested to: * Undergo 1 of 3 of the following conditions: tDCS / tPCS / sham-tPCS * Complete three sessions of cognitive tasks testing working memory, inhibition and task switching at baseline (pre-stimulation), after day 1 of brain stimulation and after 10 sessions of brain stimulation (post- repeated stimulation) * Undergo fNIRS-EEG brain measurements concurrently with the cognitive tasks

Epilepsy is one of the most common neurological diseases, affecting between 0.5% and 1% of the general population. Therefore, new diagnostic and treatment methods are having a big impact on society. Epilepsy is also one of the most commonly diagnosed pediatric neurological disorders, with long-term implications for the quality of life of those affected and their relatives. In only two-thirds of cases, seizures can be adequately controlled with anticonvulsant drug therapy. For other patients with a drug-resistant focal epilepsy (up to around 2 million in Europe) epilepsy surgery is currently the most effective treatment. However, only 15-20% of these drug-resistant patients are eligible for epilepsy surgery. This is either because the cortical epileptogenic zone cannot be localized with sufficient precision with standard diagnostic means, or because the epileptogenic zone overlaps meaningful cortical areas, so that it cannot be surgically removed without considerable neurological deficit.