Transcranial Direct Current Stimulation in Aging Research

Reward motivation and neurostimulation interact to improve working memory performance in healthy older adults: A simultaneous tDCS-fNIRS study

“…As recently reviewed by Woods et al (2019a), the reduced structural and functional connectivity, as well as atrophy, which typically characterizes the aging brain, can have a substantial influence on the conduction of electrical current, and therefore on the effect of tDCS on the underlying neuronal tissue. At the same time, atrophy seems to play a role also on the HbO levels measured with fNIRS.…”

“…The second hypothesis suggests that the variability of tDCS effects is due to inter-individual genetic differences, which are primary determinants of individual rates of neuroplasticity and/or neurotransmitter system efficiency (Dahlin et al, 2008;Stephens et al, 2017;Wiegand et al, 2016). A third relatively more recent account highlights the role of neuronal morphology, age, and cortical atrophy in explaining the variability of tDCS effects (Antonenko et al, 2018;Filmer et al, 2019;Mahdavi and Towhidkhah, 2018;Woods et al, 2019a).…”

Effects of in-Scanner Bilateral Frontal tDCS on Functional Connectivity of the Working Memory Network in Older Adults

“…tDCS is a safe and painless form of non-invasive brain stimulation that modulates the neuroplastic response of brain tissue and can impact behavior both during and after periods of stimulation through sub-threshold alteration of resting membrane potentials (Nitsche and Paulus, 2000 ; Monte-Silva et al, 2013 ; Pelletier and Cicchetti, 2015 ; Bikson et al, 2016 ; Woods et al, 2016 ; Bikson et al, 2018 ; Knotkova et al, 2019 ). Prior studies have demonstrated that tDCS can impact and enhance working memory in older adults (Jones et al, 2015 ; Woods et al, 2019a ). For example, Stephens and Berryhill ( 2016 ) demonstrated that older adults who received active tDCS over sham (anode-F4, cathode-contralateral cheek) during a working memory training protocol experienced greater benefits on untrained tasks at post-training assessment (Stephens and Berryhill, 2016 ).…”

Functional Effects of Bilateral Dorsolateral Prefrontal Cortex Modulation During Sequential Decision-Making: A Functional Near-Infrared Spectroscopy Study With Offline Transcranial Direct Current Stimulation

“…Individual anatomical peculiarities such as the topography of the cortical surface, orientation of the cortical pyramidal neurons, level of fat, cerebrospinal fluid density, and skull thickness may significantly and differently impact the flow and density of the tDCS-induced electrical currents in a variety of ways despite the same stimulation protocol, resulting in different tDCS-induced impact (Rahman et al, 2013 ; Truong et al, 2013 ; Kim et al, 2014 ; Dutta et al, 2015 ; Woods et al, 2019 ; Filmer et al, 2020 ; Habich et al, 2020 ). Sex-specific morphological differences should also be taken into consideration since they were shown to differentiate performance-related tDCS effects (León et al, 2020 ).…”

“…Despite an extensive body of research dedicated to the understanding of tDCS neuromodulatory effects and high public interest in the face of current demographic development, still little is known about the exact interplay of factors that lead to the described excitatory effects (Utz et al, 2010 ; Richardson et al, 2019 ; Habich et al, 2020 ), making the generalization, transfer, and interpretation of tDCS cumbersome (Woods et al, 2019 ). This applies also for our study despite adopting a probed RALC tDCS protocol which was shown to augment cognitive performance (Fecteau et al, 2007a ; Edgcumbe et al, 2019 ; Soyata et al, 2019 ).…”