Reconsolidation of a well-learned instrumental memory

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.