Lesser neural pattern similarity across repeated tests is associated with better long-term memory retention.

Retrieval practice reduces demands on left prefrontal brain regions implicated in cognitive control functions.

“In our prior fMRI studies we found support for that retrieval practice, as measured across three consecutive tests with (Wiklund-Hörnqvist et al., 2017) or without feedback (Karlsson Wirebring et al., 2015), reduces demands on left prefrontal brain regions implicated in cognitive control functions.”

Two studies observed greater activations related to memory enhanced by the testing effect in parietal, frontal, insular, temporal, and thalamic regions.

“Two studies observed greater activations related to memory enhanced by the testing effect in parietal, frontal, insular, temporal, and thalamic regions (Keresztes et al., 2014; Wirebring et al., 2015).”

Wirebring et al. (2015) showed reduced prefrontal cortex activation during repeated correct retrieval at the encoding phase tests, only for words subsequently remembered but not subsequently forgotten at the final test.

“This study showed reduced prefrontal cortex activation during repeated correct retrieval at the encoding phase tests, only for words subsequently remembered but not subsequently forgotten at the final test.”

The Test Group also showed greater activation for successful recall in bilateral putamen, which is consistent with a study examining successful recall for studied and tested word pairs.

“The Test Group also showed greater activation for successful recall in bilateral putamen, which is consistent with a study examining successful recall for studied and tested word pairs (Wirebring et al., 2015).”

The position of the correct answer relative to the lures was systematically varied to avoid item order effects.

“The position of the correct answer relative to the lures systematically varied to avoid item order effects (see Karlsson Wirebring et al., 2015; Wiklund-Hörnqvist et al., 2017, 2020; Jonsson et al., 2020; Stillesjö et al., 2021).”

Wirebring et al. (2015) evaluated whole-brain activations for repeatedly tested word pairs that were subsequently remembered vs. forgotten but did not compare tested vs. studied-only word pairs that were correctly recalled.

“For example, Wirebring et al. (2015) evaluated whole-brain activations for repeatedly tested word pairs that were subsequently remembered vs. forgotten but did not compare tested vs. studied-only word pairs that were correctly recalled.”

Greater variability in patterns of activation in parietal cortex across retrieval tests was associated with subsequent memory success.

“One study has provided a potential mechanistic understanding of parietal cortex contribution to repeated testing whereby greater variability in patterns of activation in parietal cortex across retrieval tests was associated with subsequent memory success (Wirebring et al., 2015).”

Our findings regarding the decreased activation of prefrontal areas in the Test Group for correct retrieval at the final test are consistent with the results of Wirebring et al. (2015).

“Our findings regarding the decreased activation of prefrontal areas in the Test Group for correct retrieval at the final test are consistent with the results of Wirebring et al. (2015).”

This reduced reliance on the frontal cortex for successful retrieval in the Test Group is consistent with results from Wirebring et al. (2015).

“This reduced reliance on the frontal cortex for successful retrieval in the Test Group is consistent with results from Wirebring et al. (2015).”

Successful retrieval at the final test is related to reduced prefrontal activation during repeated correct retrieval during encoding.

“Thus, successful retrieval at the final test is related to reduced prefrontal activation during repeated correct retrieval during encoding.”