Reconsolidation of a well-learned instrumental memory

Abstract

Once consolidated, memories are dynamic entities that go through phases of instability in order to be updated with new information, via a process of reconsolidation. The phenomenon of reconsolidation has been demonstrated in a wide variety of experimental paradigms. However, the memories underpinning instrumental behaviors are currently not believed to reconsolidate. We show that well-learned lever pressing in rats does undergo reconsolidation, which can be disrupted by systemic administration of the noncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist (+)-5-methyl-10,11-dihydro-SH-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) when administered prior to a switch to a variable, but not fixed, ratio schedule. Disruption of reconsolidation resulted in a reduction in long-term lever pressing performance and diminished the sensitivity of behavior to contingency change. Further investigation demonstrated that expression of the reconsolidation impairment was not affected by outcome value, implying a deficit in a stimulus -response (S -R) process. The ability to disrupt the performance of well-learned instrumental behaviors is potentially of great importance in the development of reconsolidation-based clinical treatments for conditions that involve compulsive seeking behaviors.

Updating memories—The role of prediction errors in memory reconsolidation

“…As discussed previously, changes in contingency may generate sufficient prediction error to initiate reconsolidation [29,36,117]. In the case of non-reinforced reactivations, the parameters that permit reconsolidation vary with training [100], consistent with the assertion that memory strength acts as a boundary condition [123].…”

“…In contrast, non-reinforced reactivation sessions have not been shown to trigger destabilisation and subsequent reconsolidation of instrumental memories [36,62,78]. In addition, training trials have also proved ineffective in instrumental settings [11,48].…”

“…new information is present [29,36,117]. Training trials do not induce reconsolidation once the contingency is well-established [29,48], however training trials can induce the reconsolidation process provided the memory is not well-learned [31,33,79,129].…”

“…Recently, we investigated whether alteration of reward contingency, rather than absolute non-reinforcement, would be sufficient to destabilise a well-learned instrumental memory [36]. In this study, rats were trained for 10 days to lever press for food reinforcement on a fixed-ratio-1 (FR1) schedule, where each lever press lead to reward delivery.…”

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

“…This implies that memory reactivation will lead to memory destabilization if, and only if, a prediction error is experienced by the animal. This hypothesis has recently found support both in humans and rats through two manipulations that induce an error prediction during memory reactivation: (a) varying the amount of CS or response exposure (Exton-McGuinness et al 2014bReichelt et al 2012Reichelt et al , 2013Sevenster et al 2012Sevenster et al , 2013Sevenster et al , 2014, and (b) varying the temporal expectation of the US presentation (Diaz-Mataix et al 2013). …”