Effects of combining retrieval practice and tDCS over long-term memory: A randomized controlled trial.

The ability to retain new information is important in daily life. In particular, two techniques have shown promise for improving long-term retention: retrieval practice (RP), which consists of actively retrieving information from long-term memory to make it more accessible in the future; and transcranial direct current stimulation (tDCS), which consists of non-invasive brain stimulation that modulates cognitive processes by increasing and decreasing neuronal excitability. Previous studies have implicated the left dorsolateral prefrontal cortex (l-dlPFC) in memory encoding and memory organization. We examined whether RP associated with a single 20-min tDCS session over the l-dlPFC could improve long-term memory retention. Participants (N = 119) repeatedly studied a list of related words either via RP or via restudy, while undergoing either anodal or sham stimulation. Participants returned 2 days later for a free-recall test. Results showed that the RP group outperformed the restudy group in all measures, regardless of stimulation type. Also, recall organization was higher in the RP group than in the restudy group. The data support previous findings and indicate that RP may enhance performance by improving the organization of the to-be-remembered list items.

Retrieval Practice in Memory- and Language-Impaired Populations: A Systematic Review.

OBJECTIVE: Neurological conditions, such as multiple sclerosis and stroke, may impair memory and language. A technique called retrieval practice (RP) may improve memory and language outcomes in such clinical populations. The RP effect refers to the finding that retrieving information from memory leads to better long-term retention than restudying the same information. Although the benefits of RP have been repeatedly observed in healthy populations, less is known about its potential applications in cognitive rehabilitation in clinical populations. Here we review the RP literature in populations with acquired memory and language impairments. METHOD: Systematic searches for studies published before January 2020 were conducted on Elsevier, PsycARTICLES, PsycINFO, Pubmed, Web of Science, and Wiley Online Library, with the terms "retrieval practice"/"testing effect" and "cognitive rehabilitation". In addition, backward and forward snowballing were used to allow the identification of important publications missed by the initial search. Studies were included if they were peer-reviewed, empirical work in which memory or language outcome measures were compared between an RP condition and a re-exposure-control condition in patients with acquired memory or language impairments. RESULTS: Sixteen articles fulfilled the inclusion criteria. Studies from memory-impaired samples were relatively homogeneous with respect to experimental protocols and materials and favored RP over control conditions. The results were mostly positive despite short retention intervals and predominantly single-session designs. Similarly, studies from language-impaired samples focused on naming impairments in patients with aphasia and also favored RP over name repetition. CONCLUSION: The results indicate that RP is a viable technique for cognitive rehabilitation.