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The Deese-Roediger-McDermott (DRM) Task: A Simple Cognitive Paradigm to Investigate False Memories in the Laboratory

The Deese,&#160;Roediger and McDermott&#160;(DRM) task is a false memory paradigm in which subjects are presented with lists of semantically related words ...

University of Notre Dame

The prefrontal cortex (PFC) regulates emotional responses, but it is unclear how PFC integrates diverse inputs to select the appropriate response. We therefore evaluated the contribution of basolateral amygdala (BLA) and ventral hippocampus (vHPC) inputs to fear signaling in the prelimbic (PL) cortex, a PFC region critical for the expression of conditioned fear. In conditioned rats trained to press for food, BLA inactivation decreased the activity of projection cells in PL, and reduced PL conditioned tone responses. In contrast, vHPC inactivation decreased activity of interneurons in PL and increased PL conditioned tone responses. Consistent with hippocampal gating of fear after extinction, vHPC inactivation increased fear and PL pyramidal activity in extinguished, but not in conditioned, rats. These results suggest a prefrontal circuit whereby hippocampus gates amygdala-based fear. Thus, deficient hippocampal inhibition of PFC may underlie emotional disorders, especially in light of reduced hippocampal volume observed in depression and PTSD.

Gating of fear in prelimbic cortex by hippocampal and amygdala inputs.

Numerous studies have investigated how stress impacts veridical memory, but how stress influences false memory formation remains poorly understood. In order to target memory consolidation specifically, a psychosocial stress (TSST) or control manipulation was administered following encoding of 15 neutral, semantically related word lists (DRM false memory task) and memory was tested 24 h later. Stress decreased recognition of studied words, while increasing false recognition of semantically related lure words. Moreover, while control subjects remembered true and false words equivalently, stressed subjects remembered more false than true words. These results suggest that stress supports gist memory formation in the DRM task, perhaps by hindering detail-specific processing in the hippocampus.

Effects of post-encoding stress on performance in the DRM false memory paradigm.

While the influence of sleep on memory has a long history, sleep's role in the formation of false memories is less clear. Moreover, virtually nothing is known about the development of false memories beyond delays of about 12h. Here, for the first time, we assess post-sleep development of true and false memories across longer delay intervals of 24 and 48h. Although technically a false memory, remembering information that is related to the theme, or gist, of an experience can be considered an adaptive process. Some evidence suggests that sleep, compared to a wake period, increases both true and gist-based false memories in the Deese-Roediger-McDermott (DRM) task, but not all studies have returned this result, and most studies cannot rule out the possibility that sleep is merely protecting the information from interference, as opposed to actively aiding its consolidation. Here, to equate amount of time spent awake and asleep across groups, we assess how the positioning of sleep relative to memory encoding impacts retention across longer delays of 24 and 48h. Participants encoded 16 DRM lists in the morning (WAKE 1st Groups) or evening (SLEEP 1st Groups), and were tested either 24 or 48h later at the same time of day. Results demonstrate that true memory is better when participants sleep soon after learning. Sleeping first also increased false memory, but only in low performers. Importantly, and similar to previous studies, we found a negative correlation between slow-wave sleep (SWS) and false memory, suggesting that SWS may be detrimental for semantic/gist processing.

Enmanuelle Pardilla-Delgado

Psychology

University of Notre Dame

The Deese-Roediger-McDermott (DRM) Task: A Simple Cognitive Paradigm to Investigate False Memories in the Laboratory

Enmanuelle Pardilla-Delgado

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Psychology

University of Notre Dame

The Deese-Roediger-McDermott (DRM) Task: A Simple Cognitive Paradigm to Investigate False Memories in the Laboratory

Psychology