%0 Journal Article
%T Task-dependent activity and connectivity predict episodic memory network-based responses to brain stimulation in healthy aging.
%A Vidal-Piñeiro D
%A Martin-Trias P
%A Arenaza-Urquijo EM
%A Sala-Llonch R
%A Clemente IC
%A Mena-Sánchez I
%A Bargalló N
%A Falcón C
%A Pascual-Leone Á
%A Bartrés-Faz D
%J Brain Stimul
%V 7
%N 2
%D Mar-Apr 2014
%M 24485466
%F 9.184
%R 10.1016/j.brs.2013.12.016
%X <B>BACKGROUND: </B>Transcranial magnetic stimulation (TMS) can affect episodic memory, one of the main cognitive hallmarks of aging, but the mechanisms of action remain unclear.<BR><B>OBJECTIVE: </B>To evaluate the behavioral and functional impact of excitatory TMS in a group of healthy elders.<BR><B>METHODS: </B>We applied a paradigm of repetitive TMS - intermittent theta-burst stimulation - over left inferior frontal gyrus in healthy elders (n = 24) and evaluated its impact on the performance of an episodic memory task with two levels of processing and the associated brain activity as captured by a pre and post fMRI scans.<BR><B>RESULTS: </B>In the post-TMS fMRI we found TMS-related activity increases in left prefrontal and cerebellum-occipital areas specifically during deep encoding but not during shallow encoding or at rest. Furthermore, we found a task-dependent change in connectivity during the encoding task between cerebellum-occipital areas and the TMS-targeted left inferior frontal region. This connectivity change correlated with the TMS effects over brain networks.<BR><B>CONCLUSIONS: </B>The results suggest that the aged brain responds to brain stimulation in a state-dependent manner as engaged by different tasks components and that TMS effect is related to inter-individual connectivity changes measures. These findings reveal fundamental insights into brain network dynamics in aging and the capacity to probe them with combined behavioral and stimulation approaches.