Remembering Our Past: Functional Neuroanatomy of Recollection of Recent and Very Remote Personal Events

TLDR

Functional magnetic resonance imaging was used to study brain regions involved in retrieving memories that are decades old, with family photographs selected by confederates to eliminate confounding variables. Context‑rich memories activated lingual and precuneus gyri regardless of age, while retrosplenial cortex was preferentially engaged for recent events; hippocampal activity correlated with vividness and showed a rostrocaudal gradient, with remote memories distributed along the axis and recent memories clustered anteriorly, findings that challenge consolidation theories and support multiple‑trace theory.

Abstract

Functional magnetic resonance imaging was used to study brain regions implicated in retrieval of memories that are decades old. To probe autobiographical memory, family photographs were selected by confederates without the participant’s involvement, thereby eliminating many of the variables that potentially confounded previous neuroimaging studies. We found that context-rich memories were associated with activity in lingual and precuneus gyri independently of their age. By contrast, retrosplenial cortex was more active for recent events regardless of memory vividness. Hippocampal activation was related to the richness of re-experiencing (vividness) rather than the age of the memory per se. Remote memories were associated with distributed activation along the rostrocaudal axis of the hippocampus whereas activation associated with recent memories was clustered in the anterior portion. This may explain why circumscribed lesions to the hippocampus disproportionately affect recent memories. These findings are incompatible with theories of long-term memory consolidation, and are more easily accommodated by multiple-trace theory, which posits that detailed memories are always dependent on the hippocampus.