Progress update from the hippocampal subfields group

Olsen, Rosanna K.; Carr, Valerie A.; Daugherty, Ana M.; Joie, Renaud La; Amaral, Robert; Amunts, Katrin; Augustinack, Jean C.; Bakker, Arnold B.; Bender, Andrew R.; Berron, David; Boccardi, Marina; Bocchetta, Martina; Burggren, Alison C.; Chakravarty, M. Mallar; Chételat, Gaël; Flores, Robin de; DeKraker, Jordan; Ding, Song‐Lin; Geerlings, Mirjam I.; Huang, Yushan; Insausti, Ricardo; Johnson, Elliott G.; Kanel, Prabesh; Kedo, Olga; Kennedy, James L.; Keresztes, Attila; Lee, Joshua K.; Lindenberger, Ulman; Mueller, Susanne; Mulligan, Elizabeth M.; Ofen, Noa; Palombo, Daniela J.; Pasquini, Lorenzo; Pluta, John; Raz, Naftali; Rodrigue, Karen M.; Shing, Yee Lee; Stark, Craig E.L.; Steve, Trevor A.; Suthana, Nanthia; Wang, Lei; Werkle‐Bergner, Markus; Yushkevich, Paul A.; Yu, Qijing; Wisse, Laura

doi:10.1016/j.dadm.2019.04.001

Cited by 51 publications

(53 citation statements)

References 47 publications

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“…The majority of studies utilize a single measure of memory or cognition, reducing the reliability, robustness, and generalizability of these constructs. Furthermore, because a unified protocol for measuring hippocampal and subfield volume has not been fully developed (see Olsen et al, in press; Wisse et al, ), prior studies have measured MTL volume based on different protocols and criteria, introducing uncontrolled error variance across studies.…”

Section: Introductionmentioning

confidence: 99%

“…Second, using structural equation modeling, we aim to investigate whether these structural measures mediate the relationship between age and memory and gauge the extent to which various models of structural connectivity may differentially account for potentially mediated relationships. In an attempt to overcome some of the weaknesses in the current literature, we utilize a harmonized hippocampal subfield segmentation protocol developed across several labs (Olsen et al, in press; Wisse et al, ), and implement multiple measurments of memory to increase the generalizability of our findings. Based on the prior literature, we hypothesize that hippocampal subfield volume and measures of fornix white matter microstructure will show negative associations with age, with the ERC exhibiting the weakest relationship, and fornix diffusion the strongest.…”

Section: Introductionmentioning

confidence: 99%

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The role of hippocampal subfield volume and fornix microstructure in episodic memory across the lifespan

et al. 2019

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Advancing age is associated with both declines in episodic memory and degradation of medial temporal lobe (MTL) structure. The contribution of MTL to episodic memory is complex and depends upon the interplay among hippocampal subfields and surrounding structures that participate in anatomical connectivity to the cortex through inputs (parahippocampal and entorhinal cortices) and outputs (fornix). However, the differential contributions of MTL system components in mediating age effects on memory remain unclear. In a sample of 177 healthy individuals aged 20–94 we collected high‐resolution T1‐weighted, ultrahigh‐resolution T2/PD, and diffusion tensor imaging (DTI) MRI sequences on a 3T Phillips Achieva scanner. Hippocampal subfield and entorhinal cortex (ERC) volumes were measured from T2/PD scans using a combination of manual tracings and training of a semiautomated pipeline. Parahippocampal gyrus volume was estimated using Freesurfer and DTI scans were used to obtain diffusion metrics from tractography of the fornix. Item and associative episodic memory constructs were formed from multiple tests. Competing structural equation models estimating differential association among these structural variables were specified and tested to investigate whether and how fornix diffusion and volume of parahippocampal gyrus, ERC, and hippocampal subfields mediate age effects on associative and/or item memory. The most parsimonious, best‐fitting model included an anatomically based path through the MTL as well as a single hippocampal construct which combined all subfields. Results indicated that fornix microstructure independently mediated the effect of age on associative memory, but not item memory. Additionally, all regions and estimated paths (including fornix) combined to significantly mediate the age‐associative memory relationship. These findings suggest that preservation of fornix connectivity and MTL structure with aging is important for maintenance of associative memory performance across the lifespan.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of hippocampal subfield volume and fornix microstructure in episodic memory across the lifespan

et al. 2019

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“…Therefore, some mild variability in correlation and accuracy versus manual segmentations is expected. Certain hippocampal boundaries (specifically along the head and the tail) are only visible in high-resolution MRIs and consensus on rules for delineating the boundaries of these regions on an MRI has not yet been reached (Olsen et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Testing a convolutional neural network-based hippocampal segmentation method in a stroke population

Zavaliangos‐Petropulu

Tubi

Haddad

et al. 2020

Preprint

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As stroke mortality rates decrease, there has been a surge of effort to study post-stroke dementia (PSD) to improve long-term quality of life for stroke survivors. Hippocampal volume may be an important neuroimaging biomarker in post-stroke dementia, as it has been associated with many other forms of dementia. However, studying hippocampal volume using MRI requires hippocampal segmentation. Advances in automated segmentation methods have allowed for studying the hippocampus on a large scale, which is important for robust results in the heterogeneous stroke population. However, most of these automated methods use a single atlas-based approach and may fail in the presence of severe structural abnormalities common in stroke. Hippodeep, a new convolutional neural network-based hippocampal segmentation method, does not rely solely on a single atlas-based approach and thus may be better suited for stroke populations. Here, we compared quality control and the accuracy of segmentations generated by Hippodeep and two well-accepted hippocampal segmentation methods on stroke MRIs (FreeSurfer 6.0 whole hippocampus and FreeSurfer 6.0 sum of hippocampal subfields). Quality control was performed using a stringent protocol for visual inspection of the segmentations, and accuracy was measured as volumetric and spatial comparisons to the manual segmentations. Hippodeep performed significantly better than both FreeSurfer methods in terms of quality control and spatial accuracy. Overall, this study suggests that both Hippodeep and FreeSurfer may be useful for hippocampal segmentation in stroke rehabilitation research, but Hippodeep may be more robust to stroke lesion anatomy.

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“…Generally, we find that the posterior SUB region in humans contains two distinct complementary gene hippocampal boundaries is highly inconsistent across studies 22,23 . Due to the difficulty of drawing hippocampal boundaries on relatively homogenous MRI contrast, the current consensus among the community is to follow geometrical selection guidelines [24][25][26][27][28][29] . However, a gene-expression based atlas could provide insight as to mechanistic and cell type-specific architecture of the hippocampus.…”

Section: Discussionmentioning

confidence: 99%

Homologous laminar organization of the mouse and human subiculum

Bienkowski

Sepehrband

Kurniawan

et al. 2019

Preprint

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The subiculum is the major output structure of the hippocampal formation and one of the brain regions most affected by Alzheimer's disease. Our previous work revealed a hidden laminar architecture within the mouse subiculum. However, the rotation of the hippocampal longitudinal axis across species makes it unclear how the laminar organization is represented in human subiculum. Using in situ hybridization data from the Allen Human Brain Atlas, we demonstrate that the human subiculum also contains complementary laminar gene expression patterns similar to the mouse. In addition, we provide evidence that the molecular domain boundaries in human subiculum correspond to microstructural differences observed in high resolution MRI and fiber density imaging. Finally, we show both similarities and differences in the gene expression profile of subiculum pyramidal cells within homologous lamina.Overall, we present a new 3D model of the anatomical organization of human subiculum and its evolution from the mouse.

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Progress update from the hippocampal subfields group

Cited by 51 publications

References 47 publications

The role of hippocampal subfield volume and fornix microstructure in episodic memory across the lifespan

The role of hippocampal subfield volume and fornix microstructure in episodic memory across the lifespan

Testing a convolutional neural network-based hippocampal segmentation method in a stroke population

Homologous laminar organization of the mouse and human subiculum

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