The tract terminations in the temporal lobe: Their location and associated functions

Claude J Bajada,Hamied A Haroon,Hojjatollah Azadbakht,Geoff J.M Parker,Matthew A Lambon Ralph,Lauren L Cloutman

doi:10.1016/j.cortex.2016.03.013

Claude J Bajada, Hamied A Haroon + Show 4 more

Open Access

https://doi.org/10.1016/j.cortex.2016.03.013

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Abstract

Temporal lobe networks are associated with multiple cognitive domains. Despite an upsurge of interest in connectional neuroanatomy, the terminations of the main fibre tracts in the human brain are yet to be mapped. This information is essential given that neurological, neuroanatomical and computational accounts expect neural functions to be strongly shaped by the pattern of white-matter connections. This paper uses a probabilistic tractography approach to identify the main cortical areas that contribute to the major temporal lobe tracts. In order to associate the tract terminations to known functional domains of the temporal lobe, eight automated meta-analyses were performed using the Neurosynth database. Overlaps between the functional regions highlighted by the meta-analyses and the termination maps were identified in order to investigate the functional importance of the tracts of the temporal lobe. The termination maps are made available in the Supplementary Materials of this article for use by researchers in the field.

Highlights

The temporal lobe has been implicated in a multitude of cognitive domains, including audition (Kaas & Hackett, 1999), vision (Goodale & Milner, 1992; Grill-Spector & Malach, 2004), language (Cloutman, 2013; Price, 2010), memory (Scoville &Milner, 1957) and semantic processing (Lambon Ralph, 2014)
The statistical termination maps for each of the tracts are presented in Fig. 2, thresholded to show voxels where a tract demonstrated greater probability of termination compared to at least half the other tracts in the pairwise comparisons
With specific areas within the temporal lobe greater than any of the other temporal tracts, both the anterior commissure (AC) and middle longitudinal fasciculus (MdLF) were associated with less connective dominance, with termination areas overlapping with other tracts

Summary

Introduction

The temporal lobe has been implicated in a multitude of cognitive domains, including audition (Kaas & Hackett, 1999), vision (Goodale & Milner, 1992; Grill-Spector & Malach, 2004), language (Cloutman, 2013; Price, 2010), memory (Scoville &Milner, 1957) and semantic processing (Lambon Ralph, 2014). Neuroanatomical, neurological and computational accounts have all emphasised that the form and pattern of the white matter connectivity will exert a strong influence over the nature of the neural computation in each area (Binney, Embleton, Jefferies, Parker, & Lambon Ralph, 2010; Brodmann, 1909; Mesulam, 1998; Plaut, 2002). These hypotheses have been supported by experimental surgical reorganisation of the major auditory and visual pathways in animals (Roe, Pallas, Kwon, & Sur, 1992; Sharma, Angelucci, & Sur, 2000; Sur, Garraghty, & Roe, 1988). In order to understand the roles played in higher cognition by different cortical regions, it is important to understand its underlying structural connectivity in detail

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