Journal article 65 views 4 downloads
The role of the fornix in human navigational learning
Cortex, Volume: 124, Pages: 97 - 110
Swansea University Author: Jiaxiang Zhang
PDF | Version of Record
© 2019 The Authors. This is an open access article under the CC BY licenseDownload (1.73MB)
Experiments on rodents have demonstrated that transecting the white matter fibre pathway linking the hippocampus with an array of cortical and subcortical structures - the fornix - impairs flexible navigational learning in the Morris Water Maze (MWM), as well as similar spatial learning tasks. While...
Check full text
No Tags, Be the first to tag this record!
Experiments on rodents have demonstrated that transecting the white matter fibre pathway linking the hippocampus with an array of cortical and subcortical structures - the fornix - impairs flexible navigational learning in the Morris Water Maze (MWM), as well as similar spatial learning tasks. While diffusion magnetic resonance imaging (dMRI) studies in humans have linked inter-individual differences in fornix microstructure to episodic memory abilities, its role in human spatial learning is currently unknown. We used high-angular resolution diffusion MRI combined with constrained spherical deconvolution-based tractography, to ask whether inter-individual differences in fornix microstructure in healthy young adults would be associated with spatial learning in a virtual reality navigation task. To efficiently capture individual learning across trials, we adopted a novel curve fitting approach to estimate a single index of learning rate. We found a statistically significant correlation between learning rate and the microstructure (mean diffusivity) of the fornix, but not that of a comparison tract linking occipital and anterior temporal cortices (the inferior longitudinal fasciculus, ILF). Further, this correlation remained significant when controlling for both hippocampal volume and participant gender. These findings extend previous animal studies by demonstrating the functional relevance of the fornix for human spatial learning in a virtual reality environment, and highlight the importance of a distributed neuroanatomical network, underpinned by key white matter pathways, such as the fornix, in complex spatial behaviour.
Hippocampus; Spatial navigation; Spatial learning; Episodic memory; Diffusion MRI
Faculty of Science and Engineering
This work was supported by funds from the Medical Research
Council (G1002149; MR/N01233X/1), a Wellcome Strategic
Award (104943/Z/14/Z), the National Institutes of Health
(R01EY025999; R01NS076856), the National Institute of
Neurological Disorders and Stroke (NSF BCS-1630296), the
European Research Council ERC starting grant (716321), and
the Wellcome Institutional Strategic Support Fund.