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

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.

Does lateral parietal cortex support episodic memory?

“…In patients with frontotemporal lobar degeneration, episodic autobiographical memory as assessed by the Autobiographical Interview was related to left inferior parietal parenchymal volume (along with bilateral temporal and left posterior cingulate/retrosplenial volumes; McKinnon et al, in press). Consistent with these patient reports, several functional neuroimaging studies of autobiographical recollection have revealed significant lateral parietal activity (e.g., Addis et al, 2004;Gilboa et al, 2004;Greenberg et al, 2005;Levine et al, 2004; for a review, see Svoboda et al, 2006), in addition to medial parietal, retrosplenial, and posterior cingulate activity. For example, Levine et al (2004) played back audiotapes of descriptions of real-life experiences to volunteers who had recorded them over several weeks.…”

Familiarity modulates the functional relationship between theory of mind and autobiographical memory

“…This pattern of activity likely reflects selfreferential and visuospatial aspects of autobiographical remembering that have been identified in previous studies (Addis et al, 2004;Epstein, 2008;Fletcher et al, 1995;Gilboa et al, 2004;Northoff et al, 2006;Rosenbaum et al, 2004;Summerfield et al, 2009;Svoboda et al, 2006).…”

“…For data analysis, we only included AM events that were successfully recollected (i.e., events rated as "remembered"), pToM and ToM events rated as novel (i.e., "nothing like a memory," corresponding to a rating of 3 or 4), and AM, pToM, and ToM events rated as vividly recollected/imagined (i.e., vividness rating of 3 or 4), as vividness is known to influence activity in regions associated with the generation of AM and ToM events (Gilboa et al, 2004;Rabin et al, 2010). We relied on the ratings participants provided during the scan, as these were believed to be more reliable than post-scan ratings.…”

In search of autobiographical memories: A PET study in the frontal variant of frontotemporal dementia

“…This left-sided involvement contrasts with findings of lesions studies which emphasize the role of right areas instead. Nevertheless, some studies emphasized the involvement of right or bilateral regions, especially the hippocampus, depending on the episodic quality of memories (e.g., Graham, Lee, Brett & Patterson, 2003;Gilboa, Winocur, Grady, Hevenor & Moscovitch, 2004;Piolino et al, 2004;Steinvorth, Corkin & Halgren, 2006;Viard et al, 2007) or on the old age of the subjects (Maguire & Frith, 2003). These data suggested that episodic autobiographical memories are triggered off in prefrontal cortex and generated through information stored in networks situated towards the posterior of the brain.…”