State modulation of hippocampal functional topography supports memory across the adult lifespan
Poster No:
1569
Submission Type:
Abstract Submission
Authors:
Kristin Nordin1, Robin Pedersen2, Farshad Falahati3, Saana Korkki1, Jarkko Johansson4, Filip Grill5, Anna Rieckmann6, Alireza Salami7
Institutions:
1Karolinska Institutet, Solna, Stockholm, 2Umeå University, Umeå, Västerbotten, 3Karolinska Institutet, Stockholm, Sweden, 4Department of Radiation Sciences, Umeå, -, 5Donders Centre for Cognitive Neuroimaging, Nijmegen, Gelderland, 6University of the Bundeswehr Munich, Munich, Bayern, 7Karolinska Institutet & Umeå University, Stockholm, Stockholm
First Author:
Co-Author(s):
Introduction:
Characterizing age-related alterations in hippocampal (HC) function is key to understanding age-related memory decline. Compared to task-free rest, naturalistic viewing more closely resembles our everyday experience and is reported to modulate HC activity in a manner that predicts memory; differs across the HC's extent; declines in aging [Reagh et al., 2020]. Compared to rest, it may enhance inter-individual differences in functional connectivity (FC), benefitting predictions of behavior [Greene et al., 2018]. Neocortical FC varies along multiple overlapping gradients within the HC [Nordin et al., 2023], the topography of which declines in aging and supports memory [Nordin et al., 2023; Przeździk et al., 2019]. Yet, it is unknown how naturalistic viewing modulates this multidimensional organization and contributes to individual differences in memory across the adult lifespan.
Methods:
Analyses included data from the DopamiNe, Age, connectoMe, and Cognition (DyNAMiC) study (N=180 healthy adults; 20-79 years; mean age=49.8±17.4; 90 women) [Nordin et al., 2022]. Functional MRI data were collected during resting state and naturalistic viewing, equal in duration and acquisition parameters. During naturalistic viewing, participants watched a sequence from the Swedish movie "Cockpit". For evaluation against HC gradients previously derived from the resting-state data [Nordin et al., 2023], gradients of HC-neocortical FC were computed for naturalistic viewing by connectopic mapping [Haak et al., 2018]. This method applies non-linear manifold learning to the similarity across voxel-wise FC fingerprints within a region. Gradients were computed at group-level and subject-level using left and right HC masks from FreeSurfer's automated segmentation [Fischl et al., 2002] of a sample-mean T1-wieghted anatomical image. Fine-scale topographic properties of gradients were parameterized through trend-surface modelling [Haak et al., 2018], for each participant and gradient yielding a set of variables used in subsequent analyses.
Results:
At a coarse scale, naturalistic-viewing gradients resembled those identified during rest [Nordin et al., 2023] (Figure 1A). We previously showed that resting-state topography of left-hemisphere G2 (separating the middle from the anterior/posterior HC), specifically, predicted episodic memory across the adult lifespan, and that older age was linked to decreased FC change across its extent [Nordin et al., 2023]. Here, analyses of gradients' topographic parameters revealed that left-hemisphere G2, specifically, displayed behaviorally relevant state-dependent modulation. Its topography differed between rest and naturalistic viewing, and its topography during naturalistic viewing significantly added to predicting episodic memory over its topography at rest. Modulation entailed an anterior-medial shift in its middle-HC anchor, indicating closer integration of uncal areas with medial posterior parietal, anterior temporal, and ventromedial prefrontal cortical areas at naturalistic viewing (Figure 1B). Older adults exhibiting a youth-like HC gradient profile during rest – and superior memory – compared to age-matched adults with dedifferentiated gradient topography, displayed a youth-like G2 also during naturalistic viewing. Importantly, older sub groups were consistently youth-like and aged in their functional modulation of G2 between states (Figure 1C).
·Figure 1. State-dependent modulation of hippocampal functional topography between resting state and naturalistic viewing
Conclusions:
Our results reveal that naturalistic viewing modulates HC functional organization in a manner that magnifies behaviorally relevant inter-individual differences. Furthermore, the specific link between memory and state-dependent modulation of G2 emphasizes the importance of not restricting functional analyses to the conventional, linear, anteroposterior understanding of HC organization. Critically, we provide novel evidence for maintenance of youth-like modulation of HC function between states as a determinant of preserved memory function in aging.
Learning and Memory:
Long-Term Memory (Episodic and Semantic)
Lifespan Development:
Aging 2
Modeling and Analysis Methods:
Connectivity (eg. functional, effective, structural) 1
Keywords:
Aging
Cognition
Memory
Other - Topographic gradients
1|2Indicates the priority used for review
Provide references using author date format
Greene AS, Gao S, Scheinost D, Constable RT (2018): Task-induced brain state manipulation improves prediction of individual traits. Nat Commun 9:2807.
Haak KV, Marquand AF, Beckmann CF (2018): Connectopic mapping with resting-state fMRI. NeuroImage 170. Segmenting the Brain:83–94.
Nordin K, Gorbach T, Pedersen R, Panes Lundmark V, Johansson J, Andersson M, McNulty C, Riklund K, Wåhlin A, Papenberg G, Kalpouzos G, Bäckman L, Salami A (2022): DyNAMiC: A prospective longitudinal study of dopamine and brain connectomes: A new window into cognitive aging. J Neurosci Res:1–25.
Nordin K, Pedersen R, Falahati F, Johansson J, Grill F, Andersson M, Korkki S, Backman L, Zalesky A, Rieckmann A, Nyberg L, Salami A (2023): Two long-axis dimensions of hippocampal cortical integration support memory function across the adult lifespan. bioRxiv. https://www.biorxiv.org/content/10.1101/2023.03.24.534115v1.
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