Prediction error and trace dominance determine the fate of fear memories after post-training manipulations

JOAQUÍN M. ALFEI; ROQUE I. FERRER MONTI; VICTOR MOLINA; BUENO, ADRIÁN MARCELO; GONZALO URCELAY

LEARNING & MEMORY (COLD SPRING HARBOR, N.Y.)

COLD SPRING HARBOR LAB PRESS

Lugar: New York; Año: 2015 vol. 22 p. 385 - 400

1072-0502

Different mnemonic outcomes have been observed when associative memories are reactivated by CS exposure and followedby amnestics. These outcomes include mere retrieval, destabilization?reconsolidation, a transitional period (which is insensitiveto amnestics), and extinction learning. However, little is known about the interaction between initial learning conditionsand these outcomes during a reinforced or nonreinforced reactivation. Here we systematically combined temporallyspecific memories with different reactivation parameters to observe whether these four outcomes are determined by theconditions established during training. First, we validated two training regimens with different temporal expectationsabout US arrival. Then, using Midazolam (MDZ) as an amnestic agent, fear memories in both learning conditions were submittedto retraining either under identical or different parameters to the original training. Destabilization (i.e., susceptiblyto MDZ) occurred when reactivation was reinforced, provided the occurrence of a temporal prediction error about USarrival. In subsequent experiments, both treatments were systematically reactivated by nonreinforced context exposureof different lengths, which allowed to explore the interaction between training and reactivation lengths. These resultssuggest that temporal prediction error and trace dominance determine the extent to which reactivation produces the differentoutcomes.