Past Experience Modulates the Neural Mechanisms of Episodic Memory Formation

Abstract

Neuroscientists have observed the "birth" of memories, but have not explored how an organism's past experience with materials interacts with the neural mechanisms of episodic memory formation. Using functional neuroimaging, we searched for such an interaction by examining brain activity during memory encoding that predicted participants' subsequent episodic memory for novel and repeated scenes. Memory for both scene types was predicted by a common posterior network in occipital and parietal cortices. Medial temporal memory predictors were modulated by scene repetition: the right anterior hippocampus and right amygdala predicted memory for novel scenes only, whereas posterior hippocampi predicted memory for repeated scenes only. There was also greater functional connectivity between the temporal pole and anterior versus posterior hippocampus, and this link predicted memory for novel but not repeated scenes. In contrast, there was greater functional connectivity between the precuneus and posterior versus anterior hippocampus, and this link predicted memory for repeated but not novel scenes. Together, these results reveal a functional specialization within the hippocampus for the encoding of novel and previously experienced materials, and suggest that the topography of this specialization might be related to local variations in connectivity. Because episodic memory for repeated scenes was superior, our results also support traditional views of encoding emphasizing the role of prior representations, and illuminate one way in which humans use existing memories to help form new ones. In so doing, our results challenge recent novelty-encoding hypotheses.

Effects of pre-experimental knowledge on recognition memory

“…Certainly, the boost in performance afforded by pre-experimental knowledge in our study far exceeds that afforded by pre-exposure to the test items in other studies Poppenk et al 2010). It may be that pre-experimental knowledge boosts the "distinctiveness" of the test items in a nonspecific way that affects both recollection-and familiarity-based recognition judgements.…”

“…Surprisingly, the impact of pre-experimental knowledge of items on performance of recognition memory tasks has only rarely been studied. Nevertheless, this factor may have a critical influence, not only on recognition performance, but also on the brain structures that are recruited during encoding and retrieval (Bird and Burgess 2008;Trinkler et al 2009;Poppenk et al 2010). The present study aimed to characterize the impact of pre-experimental knowledge on recognition memory, in particular on the parameters used to fit recognition memory data according to two models based on a dual-process theory ([DPT] recollection and familiarity) and an unequal variance signal detection ([UVSD] the magnitude and variance of the memory strength signal).…”

“…Under these conditions, recollection appears to contribute to performance, primarily by enabling subjects to reject foils that were familiar as a result of pre-exposure . A recent study using this paradigm found that source memory (which is considered to be closely related to recollection) was more accurate for pre-exposed items (Poppenk et al 2010).…”

“…This finding is not consistent with the hypothesis that pre-experimental knowledge improves performance via a selective boost in recollection of the test items, but not familiarity. It is also at odds with studies that have used pre-exposure to introduce pre-test item familiarity Poppenk et al 2010). However, this experimentally induced pre-exposure is very Figure 1.…”

Factors affecting medial temporal lobe engagement for past and future episodic events: An ALE meta-analysis of neuroimaging studies

“…The anterior hippocampus has been associated with processing environmental context (Bannerman et al, 2004;Kjelstrup et al, 2008), stimulus novelty (Strange et al, 1999;Daselaar et al, 2006;Dudukovic and Wagner, 2007;Doeller et al, 2008;Poppenk et al, 2010), arousal, emotion, reward and goal proximity (Moser and Moser, 1998;Fanselow and Dong, 2010;Royer et al, 2010;Viard et al, 2011b). The posterior hippocampus is thought to support spatial navigation (O'Keefe and Nadel, 1978;Burgess et al, 2002;Maguire et al, 1998;Ekstrom et al, 2003;Hartley et al, 2003;Moser and Moser, 1998;Doeller et al, 2008;Moser et al, 2008).…”