Marilyn S. Albert Harvard Medical School
At the beginning of the century, Müller and Pilzecker ( 1900) proposed their "perserveration-consolidation hypothesis," which stated that activity in the nervous system triggered by an event did not stop immediately but instead "perseverated." When this perseveration was complete, a stable memory trace was established. Hebb, in his seminal work The Organization of behavior, restated and expanded this theory. He proposed that two processes were necessary for the brain to retain information: First, the continual reverberation of a neural circuit and second, a structural change in neural patterns. The reverberating activity had to continue for a period of time in order for the structural change to take place. Consolidation was defined as the transformation of this temporary reverberating circuit into a permanent memory trace. Both theories therefore predicted that events that disturbed this continuing neural activity would prevent retention.
In order to evaluate the utility of this theory for an understanding of memory function, several questions need to be answered. Does a theory of consolidation make any predictions about retrograde amnesia? Are these predictions satisfied by the types of retrograde amnesia seen in animals and man? Are there patterns of remote memory loss that cannot be explained by the consolidation hypothesis?
Consolidation theory would predict that CNS intervention of an electrical, chemical, or traumatic nature that quickly follows an experience produces a memory deficit for that event. It would also predict that the duration of susceptibility to disruption is brief (i.e., seconds, minutes, or hours). The theory suggests that once reverberating neural activity has been transformed into a permanent memory trace, no loss would be expected. The study of retrograde amnesia in patients and experimental animals has produced considerable evidence for the first of these predictions but not the second. There seems no