The status of the precommissural and postcommissural fornix in normal ageing and mild cognitive impairment: An MRI tractography study

Christiansen, Kat, Aggleton, John P. ORCID: https://orcid.org/0000-0002-5573-1308, Parker, Greg D., O'Sullivan, Michael J., Vann, Seralynne D. ORCID: https://orcid.org/0000-0002-6709-8773 and Metzler-Baddeley, Claudia ORCID: https://orcid.org/0000-0002-8646-1144 2016. The status of the precommissural and postcommissural fornix in normal ageing and mild cognitive impairment: An MRI tractography study. NeuroImage 130 , pp. 35-47. 10.1016/j.neuroimage.2015.12.055

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Abstract

The fornix connects the hippocampal formation with structures beyond the temporal lobe. Previous tractography studies have typically reconstructed the fornix as one unified bundle. However, the fornix contains two rostral divisions: the precommissural fornix and the postcommissural fornix. Each division has distinct anatomical connections and, hence, potentially distinct functions. Diffusion weighted MRI and spherical deconvolution based tractography were employed to reconstruct these separate fornix divisions and to examine their microstructural properties in both healthy ageing and Mild Cognitive Impairment (MCI). Reliable reconstructions of precommissural and postcommissural fibres were achieved in both groups, with their fibres retaining largely separate locations within the anterior body of the fornix. Ageing and MCI had comparable effects on the two segments. Ageing was associated with changes in mean, axial and radial diffusivity but not with alterations of fibre population-specific diffusion properties, estimated with the hindrance modulated orientational anisotropy (HMOA). Individual HMOA variation in postcommissural, but not precommissural, fibres correlated positively (and unrelated to age) with visual recall performance. This provides novel evidence for a role of postcommissural fibres, which connect structures of the extended hippocampal network, in episodic memory function. Separating the fornix into its two principal divisions brings new opportunities for distinguishing different hippocampal networks.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Psychology Cardiff University Brain Research Imaging Centre (CUBRIC)
Subjects:	B Philosophy. Psychology. Religion > BF Psychology R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Additional Information:	This is an open access article under the terms of the CC-BY license.
Publisher:	Elsevier
ISSN:	1053-8119
Funders:	Wellcome Trust
Date of First Compliant Deposit:	30 March 2016
Date of Acceptance:	31 December 2015
Last Modified:	07 Nov 2023 11:19
URI:	https://orca.cardiff.ac.uk/id/eprint/84410

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