How a new behavioral pattern is stabilized with learning determines its persistence and flexibility in memory.

Memory organization should be at times persistent and at others flexible in the face of environmental perturbations. Unlike conceptualizations that bear on the reduction of the mismatch between the memory trace and the model, it is assumed here that changes in the memory system are governed by stability principles. Results of a bimanual coordination learning task indicated that (1) persistent memories are created and stabilized, when the competition between the preexisting (0 and 180 degrees of relative phase) and the to-be-learned (90 degrees ) patterns leads to a qualitative change in the memory layout; (2) transient memories arise without stabilization, when the competition is weaker, leading to a temporary shift of an initially stable pattern (90 degrees ) toward the required value (135 degrees ). These findings call for further examination of the relationship between stability and memory persistence, which might give a new thrust to understanding its neural correlates.