This study will investigate the extent to which tDCS to dorsolateral prefrontal cortex (or dlPFC) impacts memory performance as a function of time-of-day in younger and older adults.
Transcranial Direct Current Stimulation (tDCS) is the safest and most accessible, non-invasive brain stimulation technique available for testing causal links between different brain regions and functions, by manipulating cognitive abilities. By identifying key experimental factors that can improve the reliability and robustness of stimulation effects on cognitive performance in different age groups, this project should lead to the widespread adoption of these design features in future applications. This study will investigate the extent to which tDCS to dorsolateral prefrontal cortex (or dlPFC) impacts recollection accuracy and working memory performance as a function of time-of-day in younger and older adults. Moreover, this study will test the extent that tDCS to dlPFC impacts memory performance by impacting information-specific processes and/or cognitive control processes that operate across different types of information, thereby informing basic theories of how dlPFC contributes to memory in younger and older adults.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
271
The brain is stimulated for 20 minutes with mild electrical current (maximum 2 mA) with two 7 cm x 5 cm electrodes placed on the scalp, using a standard 1x1 tDCS Clinical Trials device (Soterix Medica, NY), specialized for double-blinding.
The brain is not stimulated for 20 minutes with mild electrical current, but instead a sham procedure is administered using a standard 1x1 tDCS Clinical Trials device (Soterix Medica, NY), specialized for double-blinding.
University of Chicago
Chicago, Illinois, United States
Episodic Memory Performance
To measure episodic memory performance, participants will perform a recollection task. They will first study picture and word stimuli (encoding phase). On the subsequent memory test (retrieval phase), participants will be asked to differentiate between studied and non-studied items, as well as recollecting the previous format for studied items (i.e. recollecting the picture or word). For each tested item, participants will also be asked to make a confidence judgement about their response. The primary dependent variable (DV) will be the proportion of studied items attributed to the correct source minus the proportion of nonstudied items incorrectly attributed to that same source.
Time frame: This task is performed immediately after tDCS is administered, and lasts approximately 20 minutes.
Working Memory Performance
To measure working memory performance, participants will perform two versions of the N-back task -- a verbal version (i.e., presenting the numbers 1-9 in a varied sequence) and a visuospatial version (i.e., presenting a colored square in one of 9 locations on a 3x3 grid in a varied sequence). The primary DV will be working memory accuracy: proportion of targets correctly identified minus the proportion of lures incorrectly endorsed.
Time frame: This task lasts approximately 10 minutes and is performed immediately after the episodic memory task (approximately 20 minutes after the end of the tDCS session).
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