Dissecting medial temporal lobe contributions to item and associative memory formation

Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, 6500 HB Nijmegen, The Netherlands.
NeuroImage (Impact Factor: 6.36). 04/2009; 46(3):874-81. DOI: 10.1016/j.neuroimage.2009.02.039
Source: PubMed

ABSTRACT A fundamental and intensively discussed question is whether medial temporal lobe (MTL) processes that lead to non-associative item memories differ in their anatomical substrate from processes underlying associative memory formation. Using event-related functional magnetic resonance imaging, we implemented a novel design to dissociate brain activity related to item and associative memory formation not only by subsequent memory performance and anatomy but also in time, because the two constituents of each pair to be memorized were presented sequentially with an intra-pair delay of several seconds. Furthermore, the design enabled us to reduce potential differences in memory strength between item and associative memory by increasing task difficulty in the item recognition memory test. Confidence ratings for correct item recognition for both constituents did not differ between trials in which only item memory was correct and trials in which item and associative memory were correct. Specific subsequent memory analyses for item and associative memory formation revealed brain activity that appears selectively related to item memory formation in the posterior inferior temporal, posterior parahippocampal, and perirhinal cortices. In contrast, hippocampal and inferior prefrontal activity predicted successful retrieval of newly formed inter-item associations. Our findings therefore suggest that different MTL subregions indeed play distinct roles in the formation of item memory and inter-item associative memory as expected by several dual process models of the MTL memory system.

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Available from: Shaozheng Qin, Aug 16, 2015
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    • "Several neuroimaging studies have reported that during encoding, neural activity in the frontal, occipital, and medial temporal regions differs according to whether the related source of the item was remembered in a subsequent memory test [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] . These differences in neural activity are often described as " subsequent source memory effects " [14] . "
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    Neural Regeneration Research 09/2013; 8(26):2424-31. DOI:10.3969/j.issn.1673-5374.2013.26.003 · 0.23 Impact Factor
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    • "These findings support the view that components of the MTL perform qualitatively distinct computations and that this heterogeneity of function does not simply reflect memory strength (Montaldi & Mayes, 2010). The data are also consistent with dual-process models of the neural bases of recognition memory (Aggleton & Brown, 2006; Brown & Aggleton, 2001; Diana et al., 2007; Mayes et al., 2007; Montaldi & Mayes, 2010) and other studies distinguishing between the roles of the PRC and the hippocampus with respect to familiarity and recollection (e.g., Cohn et al., 2009; Davachi et al., 2003; Diana et al., 2010; Greve, Evans, Graham, & Wilding, 2011; Montaldi et al., 2006; Qin et al., 2009; Ranganath et al., 2004; Yonelinas et al., 2005; but see Kirwan et al., 2008; Smith, Wixted, & Squire, 2011; Song, Jeneson, & Squire, 2011). "
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    ABSTRACT: Two experiments explored eye measures (fixations and pupil response patterns) and brain responses (BOLD) accompanying the recognition of visual object stimuli based on familiarity and recollection. In both experiments, the use of a modified remember/know procedure led to high confidence and matched accuracy levels characterising strong familiarity (F3) and recollection (R) responses. In Experiment 1, visual scanning behaviour at retrieval distinguished familiarity-based from recollection-based recognition. Recollection, relative to strength-matched familiarity, involved significantly larger pupil dilations and more dispersed fixation patterns. In Experiment 2, the hippocampus was selectively activated for recollected stimuli, while no evidence of activation was observed in the hippocampus for strong familiarity of matched accuracy. Recollection also activated the parahippocampal cortex (PHC), while the adjacent perirhinal cortex (PRC) was actively engaged in response to strong familiarity (than to recollection). Activity in prefrontal and parietal areas differentiated familiarity and recollection in both the extent and the magnitude of activity they exhibited, while the dorsomedial thalamus showed selective familiarity-related activity, and the ventrolateral and anterior thalamus selective recollection-related activity. These findings are consistent with the view that the hippocampus and PRC play contrasting roles in supporting recollection and familiarity and that these differences are not a result of differences in memory strength. Overall, the combined pupil dilation, eye movement and fMRI data suggest the operation of recognition mechanisms drawing differentially on familiarity and recollection, whose neural bases are distinct within the MTL.
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    • "As their attempt to explain the impact of self-descriptiveness on memory formation, Rogers et al. (1977) speculated that relevant items lead to enhanced relational binding as those items can be more readily integrated into a preexisting cognitive network and consequently strengthen the memory trace. Indeed, the hippocampus has been held to play a key role in binding various episodic details irrespective of encoding task (Davachi et al., 2003; Ranganath et al., 2003; Kensinger and Schacter, 2006; Uncapher et al., 2006; Dougal et al., 2007; Qin et al., 2009; Staresina and Davachi, 2009). This may suggests that the memory boost for relevant items relies on the enhanced relational binding mechanisms employed during relevant trials. "
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