The effects of anodal transcranial direct current stimulation on cortical and behavioural changes: An investigation of counter-regulatory mechanisms

Transcranial direct current stimulation (tDCS) is a non-invasive brain neuromodulatory technique for induction of changes in the activity and excitability of the brain. Long term potentiation- (LTP) like plasticity is induced when anodal tDCS (a-tDCS) is applied over the primary motor cortex. It has been shown that specific parameters of a-tDCS can induce different effects on corticospinal excitability (CSE) in different individuals. While, not much is known about the exact stimulation parameters for reversals, and non-linearities, as well as underlying mechanisms, therefore, the studies introduced in this thesis are motivated by the need to explore if changing duration and intensity of stimulation would affect the effect of a-tDCS on CSE and even reverse it. Moreover, it was aimed to investigate if changes on CSE following a-tDCS would affect a motor performance task.