A species-general, retrieval-specific mechanism of adaptive forgetting in the mammalian brain

PEDRO BEKINSCHTEIN; MICHAEL ANDERSON; FRANCISCO GALLO; NOELIA WEISSTAUB

Budapest

Congreso; International Conference on Memory 2016; 2016

ICOM

Neurobiological research on memory often presumes that forgetting is a negative outcome arising from passive mechanisms such as decay and interference. In the last two decades, however, a growing literature with human participants has revealed adaptive forgetting mechanisms that actively impair interfering memories via inhibitory control. Here we report an animal model of adaptive forgetting that establishes, for the first time, that its central theoretical properties are conserved across species. Using spontaneous object recognition, we found that when rats selectively retrieved a memory of an object encountered in a particular context, it dramatically impaired competing memories of other objects encountered in that context. Critically, in agreement with the inhibitory control hypothesis, this retrieval-induced forgetting was competition-dependent, cue-independent, long-lasting, and reliant on control mechanisms mediated by the medial prefrontal cortex. As competing memories were inhibited over repetitions, medial prefrontal cortex engagement declined, reflecting a key adaptive benefit of forgetting. These findings demonstrate a species-general adaptive forgetting process and establish an animal model that permits the study of its circuit-level, cellular and molecular mechanisms.