A role for the fornix in temporal sequence memory

Read, Marie-Lucie; Umla-Runge, Katja; Lawrence, Andrew David; Costigan, Alison G.; Hsieh, Liang‐Tien; Chamberland, Maxime; Ranganath, Charan; Graham, Kim S.

doi:10.1111/ejn.15940

Cited by 3 publications

References 130 publications

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Implications of fitting a two-compartment model in single-shell diffusion MRI

Chad,

Sochen,

Chen

et al. 2023

Phys. Med. Biol.

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It is becoming increasingly common for studies to fit single-shell diffusion MRI data to a two-compartment model, which comprises a hindered cellular compartment and a freely diffusing isotropic compartment. These studies consistently find that the fraction of the isotropic compartment (f) is sensitive to white matter (WM) conditions and pathologies, although the actual biological source of changes in f has not been validated. In this work we put aside the biological interpretation of f and study the sensitivity implications of fitting single-shell data to a two-compartment model. We identify a nonlinear transformation between the one-compartment model (diffusion tensor imaging, DTI) and a two-compartment model in which the mean diffusivities of both compartments are effectively fixed. While the analytic relationship implies that fitting this two-compartment model does not offer any more information than DTI, it explains why metrics derived from a two-compartment model can exhibit enhanced sensitivity over DTI to certain types of WM processes, such as age-related WM differences. The sensitivity enhancement should not be viewed as a substitute for acquiring multi-shell data. Rather, the results of this study provide insight into the consequences of choosing a two-compartment model when only single-shell data is available.

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Implications of fitting a two-compartment model in single-shell diffusion MRI

Chad,

Sochen,

Chen

et al. 2023

Phys. Med. Biol.

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Multimodal MEG and microstructure-MRI investigations of the human hippocampal scene network

Lucie-Read,

Hodgetts,

Lawrence

et al. 2024

Preprint

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Although several studies, including our own (Hodgetts et al., 2015), have demonstrated that perceptual discrimination of complex scenes relies on an extended hippocampal network, distinct from the anterotemporal network supporting the perceptual discrimination of faces, we currently have limited insight into the specific functional and structural properties of these networks. Here, combining electrophysiological (magnetoencephalography, MEG) and microstructural (multi-shell diffusion MRI, dMRI) imaging in healthy human adults, we show that both hippocampal theta power modulation and fibre restriction of the fornix (a major input/output pathway of the hippocampus) independently related to accuracy during scene, but not face, perceptual discrimination. Conversely, inferior longitudinal fasciculus (a long-range occipito-anterotemporal tract) tissue properties correlated with face, but not scene, oddity discrimination accuracy. Our results provide new mechanistic insight into the neurocognitive systems underpinning complex scene and face perception, providing support for multiple-system representation-based accounts of the medial temporal lobe.

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A role for the fornix in temporal sequence memory

Read

Umla-Runge

Lawrence

et al. 2023

Eur J of Neuroscience

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Converging evidence from studies of human and nonhuman animals suggests that the hippocampus contributes to sequence learning by using temporal context to bind sequentially occurring items. The fornix is a white matter pathway containing the major input and output pathways of the hippocampus, including projections from medial septum and to diencephalon, striatum, lateral septum and prefrontal cortex. If the fornix meaningfully contributes to hippocampal function, then individual differences in fornix microstructure might predict sequence memory. Here, we tested this prediction by performing tractography in 51 healthy adults who had undertaken a sequence memory task. Microstructure properties of the fornix were compared with those of tracts connecting medial temporal lobe regions but not predominantly the hippocampus: the Parahippocampal Cingulum bundle (PHC) (conveying retrosplenial projections to parahippocampal cortex) and the Inferior Longitudinal Fasciculus (ILF) (conveying occipital projections to perirhinal cortex). Using principal components analysis, we combined Free-Water Elimination Diffusion Tensor Imaging and Neurite Orientation Dispersion and Density Imaging measures obtained from

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A role for the fornix in temporal sequence memory

Cited by 3 publications

References 130 publications

Implications of fitting a two-compartment model in single-shell diffusion MRI

Implications of fitting a two-compartment model in single-shell diffusion MRI

Multimodal MEG and microstructure-MRI investigations of the human hippocampal scene network

A role for the fornix in temporal sequence memory

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