TMS for Investigating Memory Facilitation

The fundamental objective is to evaluate the changes derived from the specific Paired Associative Stimulation (PAS) protocol applying Transcranial Magnetic Stimulation (TMS) towards the hippocampus to enhance memory in an older population. We will evaluate the following effects: 1) Changes in memory capacity using task performance of the working memory (WM) task and calculating the correctly memorized items; and 2) Changes in brain connectivity using resting state functional Magnetic Resonance Imaging (rs-fMRI) and comparing the correlated activity between areas related to the process of memorization. In order to understand the memory and brain connectivity changes derived from the PAS intervention more specifically, we will characterize the stimulation localization, the Inter Stimulus Interval (ISI) timing and rule out training and placebo effects. To research if the PAS effects are specific to the stimulated brain area, we will conduct a control group in which stimulation will be delivered to the primary motor area (M1). Then, we will compare the outcome measures (changes in memory capacity and brain connectivity) between the different brain areas. To characterize the ISI, our goal is to calculate the synchronization timing that triggers cortical plastic changes. Thus, we will test two different ISI between the TMS pulse delivery and memorization task. Finally, to differentiate the effects that are derived from the PAS versus the effects from repetition of the task or placebo effects, we will conduct another control group with Sham TMS stimulation and reproduce the same experimental procedures as the group that receives the TMS stimulation. Sham TMS is used in this study to compare if brain stimulation (active TMS) can help improve memory compared to receiving no brain stimulation (sham TMS).