Intermittent theta burst stimulation over left BA10 enhances virtual reality-based prospective memory in healthy aged subjects

Prospective memory (PM) refers to a complex cognitive ability that underpins the delayed execution of previously formulated intentions. PM performance declines early in normal aging and this process is accentuated in Alzheimer's disease. The left frontopolar cortex (BA10) has been consistently assigned a major role in PM functioning, but whether it can be noninvasively modulated to enhance PM performance in aged people has not been addressed so far. Here, we investigated the effects of modulating left BA10 by means of theta burst stimulation (TBS), using either excitatory (intermittent TBS), inhibitory (continuous TBS) or control (vertex) TBS in healthy aged subjects. The behavioral effects were assessed using a reliable and ecological virtual reality PM task that included both event- and time-based retrievals. As compared with vertex stimulation, event-based PM performance significantly improved after excitatory stimulation, whereas inhibitory stimulation had no significant effect. Additionally, and across the different types of stimulation, performance for congruent links between the event-based PM cue and the action to be performed was significantly better as compared with incongruent links. In conclusion, intermittent TBS might provide a relevant interventional strategy to counteract the decline of cognitive functions and memory abilities in normal aging.