Transcranial brain stimulation studies of episodic memory in young adults, elderly adults and individuals with memory dysfunction: a review.

Transcranial magnetic and electric stimulation studies examining episodic memory in young participants have established the role of the left prefrontal cortex during encoding and the right prefrontal cortex during episodic retrieval. Furthermore, these techniques have been used to verify the reduction in functional asymmetry in the prefrontal cortex that occurs with ageing, at least during encoding, suggesting the existence of compensatory adjustments for the structural and neurotransmitter loss that occurs with physiological ageing. Nevertheless, it has been shown that several factors can modulate performance based on the type of material or strategy used. It is important to note that although numerous studies have addressed the role of the prefrontal cortex in episodic memory, a number of studies have also demonstrated the involvement of a more distributed neural network sustaining this function involving the temporal lobes and parietal cortices. Finally, it is evident that the use of transcranial stimulation techniques might represent a powerful tool not only for investigating the involvement of cerebral areas in a specific cognitive task but also for designing interventional therapies for individuals with memory impairment.