Distribution and fibre field similarity mapping of

Authors: Markand Dipankumar Patel Nicolas Toussaint Geoffrey David CharlesEdwards JeanPierre Lin Philip G Batchelor

Publish Date: 2010/03/13

Volume: 23, Issue: 5-6, Pages: 399-408

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Abstract

The anterior commissure is a critical interhemispheric pathway in animals yet its connections in humans are not clearly understood Its distribution has shown to vary greatly between species and it is thought that in humans it may convey axons from a larger territory than previously thought The aim was to use an anatomical mapping tool to look at the anterior commissure fibres and to compare the distribution findings with published anatomical understandingTwo different diffusionweighted imaging data sets were acquired from eight healthy subjects using a 3 Tesla MR scanner with 32 gradient directions Diffusion tensor imaging tractography was performed and the anterior commissure fibres were selected using threedimensional regions of interest Distribution of the fibres was observed by means of registration with T2weighted images The fibre field similarity maps were produced for five of the eight subjects by comparing each subject’s fibres to the combined map of the five data setsFibres were shown to lead into the temporal lobe and towards the orbitofrontal cortex in the majority of subjects Fibres were also distributed to the parietal or occipital lobes in all five subjects in whom the anterior commissure was large enough for interhemispheric fibres to be tracked through The fibre field similarity maps highlighted areas where the local distances of fibre tracts were displayed for each subject compared to the combined bundle mapThe anterior commissure may play a more important role in interhemispheric communication than currently presumed by conveying axons from a wider territory and the fibre field similarity maps give a novel approach to quantifying and visualising characteristics of fibre tracts

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