[The consolidation of memory, one century on]

The theory of memory consolidation, based on the work published by Georg Elias Muller and Alfons Pilzecker over a century ago, continues to guide research into the neurobiology of memory, either directly or indirectly. In their classic monographic work, they concluded that fixing memory requires the passage of time (consolidation) and that memory is vulnerable during this period of consolidation, as symptoms of amnesia appear when brain functioning is interfered with before the consolidation process is completed. Most of the experimental data concerning this phenomenon strongly support the theory.

In this article we present a review of experiments that have made it possible to put forward a model that explains the amnesia produced in conventional learning conditions, as well as another model related to the protection of memory when the same instances of learning are submitted to a situation involving intensive training.

Findings from relatively recent studies have shown that treatments that typically produce amnesia when they are administered immediately after a learning experience (during the period in which the memory would be consolidating itself) no longer have any effect when the instances of learning involve a relatively large number of trials or training sessions, or relatively high intensity aversive events. These results are not congruent with the prevailing theories about consolidation.