Targeted enhancement of cortical-hippocampal brain networks and associative memory

Abstract

The influential notion that the hippocampus supports associative memory by interacting with functionally distinct and distributed brain regions has not been directly tested in humans. We therefore used targeted noninvasive electromagnetic stimulation to modulate human cortical-hippocampal networks and tested effects of this manipulation on memory. Multi-session stimulation increased functional connectivity among distributed cortical-hippocampal network regions and concomitantly improved associative memory performance. These alterations involved localized long-term plasticity, because increases were highly selective to the targeted brain regions, and enhancements of connectivity and associative memory persisted for ~24 hours following stimulation. Targeted cortical-hippocampal networks can thus be enhanced noninvasively, demonstrating their role in associative memory.

Adenosine A 1 receptor antagonist rolofylline alleviates axonopathy caused by human Tau ΔK280

“…Stimulation of the perforant path in an Aβ-based mouse model is sufficient to restore memory retrieval (40). Similarly, transcranial magnetic stimulation in humans increases brain network activity and performance of associative memory, emphasizing the benefit of increased bona fide network activity (41). In conclusion, we show that Tau protein impairs neurons through its ability to aggregate, which in turn leads to reduced neuronal activity, lowered ATP levels, and dendritic spine loss.…”

Neurochemical Modulation in Posteromedial Default-mode Network Cortex Induced by Transcranial Magnetic Stimulation

“…However NIBS after-effects are highly dependent on a variety of parameters [27] such as functional brain connectivity that mediates the neural and cognitive response to NIBS [26,28]. rTMS can directly modulate DMN expression [29,30] by targeting an accessible cortical node of this network; the left IPL. So far, it has been shown that stimulating this area modulates connectivity changes between DMN nodes [30,31] and enhances alpha rhythm [32].…”

A network approach for modulating memory processes via direct and indirect brain stimulation: Toward a causal approach for the neural basis of memory

“…In contrast, one TMS study reported improvements in recall of previously learned items following stimulation of parietal cortex (Wang et al, 2014). Resting state fMRI was used to target putative connections from parietal cortex to the hippocampus, and memory improvements due to stimulation were attributed to activating long-term potentiation in cortical-hippocampal synapses.…”