Disentangling the Role of the MEC and LEC in the Processing of Spatial and Non-Spatial Information: Contribution of Lesion Studies

Save, Étienne; Sargolini, Francesca

doi:10.3389/fnsys.2017.00081

Cited by 48 publications

(31 citation statements)

References 81 publications

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“…This might indicate that the LEC is the source of temporal information provided to distal CA1. Preliminary data from the Moser laboratory using population-level analyses of electrohysiological recordings partly support this hypothesis by reporting that LEC’s involvement within this frame depends on tasks’ demands, with free foraging tasks eliciting a stronger temporal representation in the LEC than continuous alternation/back-and-forth running tasks [ 69 ]; of note, such tasks’ demand dependency in the LEC were also reported in recent lesion and Arc imaging studies, albeit for the processing object and space information [ 70 , 71 ]. Our findings of a preferential involvement of distal CA1 in time processing depart from the standard model of episodic memory which, by extrapolation, predicts that temporal information would rather be processed by proximal CA1 because it mainly receives projections from the MEC, a part of the “where–when” pathway [ 2 , 4 ].…”

Section: Discussionmentioning

confidence: 78%

The memory for time and space differentially engages the proximal and distal parts of the hippocampal subfields CA1 and CA3

et al. 2018

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A well-accepted model of episodic memory involves the processing of spatial and non-spatial information by segregated pathways and their association within the hippocampus. However, these pathways project to distinct proximodistal levels of the hippocampus. Moreover, spatial and non-spatial subnetworks segregated along this axis have been recently described using memory tasks with either a spatial or a non-spatial salient dimension. Here, we tested whether the concept of segregated subnetworks and the traditional model are reconcilable by studying whether activity within CA1 and CA3 remains segregated when both dimensions are salient, as is the case for episodes. Simultaneously, we investigated whether temporal or spatial information bound to objects recruits similar subnetworks as items or locations per se, respectively. To do so, we studied the correlations between brain activity and spatial and/or temporal discrimination ratios in proximal and distal CA1 and CA3 by detecting Arc RNA in mice. We report a robust proximodistal segregation in CA1 for temporal information processing and in both CA1 and CA3 for spatial information processing. Our results suggest that the traditional model of episodic memory and the concept of segregated networks are reconcilable, to a large extent and put forward distal CA1 as a possible “home” location for time cells.

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Section: Discussionmentioning

confidence: 78%

The memory for time and space differentially engages the proximal and distal parts of the hippocampal subfields CA1 and CA3

et al. 2018

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“…However, we hasten to add that these results should be interpreted with caution given the small sample (n = 21) and that they should be replicated in a larger study. Moreover, there is evidence that the medial and lateral portions of ERC play divergent roles in memory 62,68,69 , so it will be important for future studies to segment the ERC into these subsections.…”

Section: Discussionmentioning

confidence: 99%

Links between autobiographical memory richness and temporal discounting in older adults

Lempert¹,

MacNear²,

Wolk³

et al. 2020

Sci Rep

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When making choices between smaller, sooner rewards and larger, later ones, people tend to discount future outcomes. Individual differences in temporal discounting in older adults have been associated with episodic memory abilities and entorhinal cortical thickness. the cause of this association between better memory and more future-oriented choice remains unclear, however. one possibility is that people with perceptually richer recollections are more patient because they also imagine the future more vividly. Alternatively, perhaps people whose memories focus more on the meaning of events (i.e., are more "gist-based") show reduced temporal discounting, since imagining the future depends on interactions between semantic and episodic memory. We examined which categories of episodic details-perception-based or gist-based-are associated with temporal discounting in older adults. older adults whose autobiographical memories were richer in perception-based details showed reduced temporal discounting. furthermore, in an exploratory neuroanatomical analysis, both discount rates and perception-based details correlated with entorhinal cortical thickness. Retrieving autobiographical memories before choice did not affect temporal discounting, however, suggesting that activating episodic memory circuitry at the time of choice is insufficient to alter discounting in older adults. These findings elucidate the role of episodic memory in decision making, which will inform interventions to nudge intertemporal choices. Throughout our lives, we face many intertemporal choices that involve trade-offs between smaller, immediate gains and larger, long-term benefits 1. For example, an individual may have to decide whether or not it is worth paying a fee to withdraw retirement funds early. People generally tend to prefer immediate rewards to delayed ones, and they discount the value of delayed rewards to a greater extent as the delay to receiving them increases. This tendency towards temporal discounting is nearly universal, but the rate at which people discount future rewards varies widely 2,3. Steep temporal discounting, or overvaluing the present at one's long-term expense, is associated with risky behaviors such as alcohol use 4 , gambling 5 , smoking 6,7 , and excessive credit card borrowing 8. Given the substantial negative impact of steep temporal discounting, it is important to understand the neurocognitive mechanisms that underlie intertemporal choices, and to use this knowledge to develop interventions that could reduce impatience. The literature on the neural correlates of temporal discounting points to the involvement of valuation regions 9-11 , executive control regions 12-15 and episodic memory regions 16,17 in this choice process. It remains unclear, however, which of these neurocognitive systems underlies individual differences in the tendency to discount future rewards. One neurocognitive system that may support future-oriented intertemporal choices is episodic memory, or context-rich memory for autobiographical events 1...

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“…Additionally, while many studies have investigated grid coding during free foraging tasks, a recent study found that introducing reward locations altered the structure of grid cells in medial entorhinal cortex to preferentially represent the reward location (Butler, Hardcastle, & Giocomo, ). More generally, other findings have suggested that the involvement of entorhinal cortex in navigation can vary based on environmental features (Barry, Ginzberg, O'keefe, & Burgess, ; Stensola & Moser, ) and behavioral demands (Rodo, Sargolini, & Save, ; Save & Sargolini, ; Yoo & Lee, ). Together, these findings reveal that grid cell coding in the entorhinal cortex is inconsistently hexagonally symmetric, rarely static, and is flexible.…”

Section: What About Situations Involving Neural Recordings Of Grid Cementioning

confidence: 98%

“…Additionally, in one study, reducing grid cell activity using optogenetics had no observable effect on Morris Water Maze performance (Kanter et al, ). Overall, the effects of perturbing medial entorhinal cortex are somewhat task specific and do not consistently impair allocentric navigation or situations that might appear to necessitate a spatial metric (for a review, see: Save & Sargolini, ).…”

Section: What About Situations Involving Neural Recordings Of Grid Cementioning

confidence: 99%

Grid coding, spatial representation, and navigation: Should we assume an isomorphism?

2019

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Grid cells provide a compelling example of a link between cellular activity and an abstract and difficult to define concept like space. Accordingly, a representational perspective on grid coding argues that neural grid coding underlies a fundamentally spatial metric. Recently, some theoretical proposals have suggested extending such a framework to nonspatial cognition as well, such as category learning. Here, we provide a critique of the frequently employed assumption of an isomorphism between patterns of neural activity (e.g., grid cells), mental representation, and behavior (e.g., navigation). Specifically, we question the strict isomorphism between these three levels and suggest that human spatial navigation is perhaps best characterized by a wide variety of both metric and nonmetric strategies. We offer an alternative perspective on how grid coding might relate to human spatial navigation, arguing that grid coding is part of a much larger conglomeration of neural activity patterns that dynamically tune to accomplish specific behavioral outputs.

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Disentangling the Role of the MEC and LEC in the Processing of Spatial and Non-Spatial Information: Contribution of Lesion Studies

Cited by 48 publications

References 81 publications

The memory for time and space differentially engages the proximal and distal parts of the hippocampal subfields CA1 and CA3

The memory for time and space differentially engages the proximal and distal parts of the hippocampal subfields CA1 and CA3

Links between autobiographical memory richness and temporal discounting in older adults

Grid coding, spatial representation, and navigation: Should we assume an isomorphism?

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