Introduction
epilepsy
EVENTS, EPILEPSY
Our ability to recall context-based information, such as events and personal experiences, is fundamental to everyday functioningThe therapeutic use of electrical stimulation is an area that has received a great deal of research in recent years, particularly in the context of memory. A large portion of the research exploring stimulation and cognition has used transcranial direct current stimulation (tDCS), where a low electrical current (typically 1–2 mA) is introduced to the scalp via two electrodesWhen performing any cognitive task, synchronised neural oscillations facilitate the local and distal communication of brain regions involved in the functional networkThe mechanism by which tDCS and tACS apply electrical current to the brain is fundamentally different. tDCS applies electrical currents through multiple scalp electrodes and is thought to modulate the excitability of neuronal populations, depending on whether a positive charge (anodal, excitatory) or negative charge (cathodal, inhibitory) is applied. While tACS also applies electrical current through scalp electrodes, it utilises an oscillating sinusoidal current (i.e., more closely resembling normal brain activity) to modulate rhythmic cortical network activity(In the present study, we aimed to investigate whether anodal tDCS and theta tACS (using 6 Hz stimulation) can improve episodic verbal memory performance in healthy adults, when applied to the left temporal lobe. We hypothesised that 1) both tDCS and theta tACS would improve memory performance compared to sham, as the literature suggests that the introduction of electrical activity to the temporal lobe is typically associated with improved memory performance, and 2) that tACS would result in a greater improvement in recall performance compared to tDCS, through the use of theta frequency stimulation. An understanding of the comparative effects of these stimulation methods on memory performance is vital when investigating the therapeutic effects of stimulation in clinical cohorts, such as AD and epilepsy.