Consolidating dispersed neocortical memories: the missing link in amnesia

Consolidation is often conceptualised as a general process by which memory traces can be strengthened in the brain. An alternative idea, developed here, is that a particular sort of consolidation is required for establishing memories belonging to a neurobiologically defined category-memories dispersed across multiple distinct neocortical zones. These memories are consolidated via the formation of a neocortical cell assembly that confers coherence to the set of scattered neocortical memory traces. A set of memory traces linked in this manner can subsequently serve as the basis for conscious recollection. A disruption of this neocortical consolidation process is held to be responsible for the patterns of preserved and impaired memory observed in amnesic patients. A suitable strategy for empirically testing this sort of theory requires an examination of evidence from neuropsychological studies of amnesia and from studies of the neural substrates of memory functions in normal subjects.