A Diffusion Tractography Investigation of the Shared and Distinct White Matter Tracts that Underlie Language and Theory of Mind

Leo Zekelman, BA
Department of Neurosurgery
Division of Basic Neuroscience Research
Poster Overview

Comprehending the intended meaning of an utterance depends not only on the ability to understand words but also upon the ability interpret the emotional states in which they are produced. That is, miscommunications may easily arise when listeners do not know what the words refer to or are oblivious to the speaker’s emotional mental state. We examine the brain structures that may be functionally shared allowing for successful communication and the brain structures that may be functionally separate supporting our daily communication struggles. To better understand how word comprehension and emotion recognition are physically manifested in the brain, we use a non-invasive neuroimaging technique known as diffusion MRI to examine the brain’s major wiring system, the white matter tracts, in over 900 brains of healthy participants. We find support for both shared and distinct white matter tracts that may underlie communication through words and emotions.

Scientific Abstract

Successful communication depends jointly on the ability to understand words and others’ emotional states. Often described as foundational components of language and theory of mind (ToM), these lifelong skills develop simultaneously during childhood, pointing to their possible shared roots. However, functional MRI research demonstrates that language and ToM belong to distinct networks that lateralize to opposite hemispheres. To explore their distinction and interrelation, we examine how two foundational measures of language and ToM (i.e. Toolbox Picture Vocabulary Test (TPVT) and Penn Emotion Recognition Test (PERT)) relate to diffusion MRI data collected from 965 healthy young adults in the Human Connectome Project. We consistently parcellate the white matter (WM) by applying a neuroanatomically curated WM atlas that leverages machine learning to identify the WM tracts in each participant’s brain (Zhang et al., 2018). Properties of white matter tract microstructure were measured including the mean fractional anisotropy (FA), mean diffusivity (MD), and number of fibers across 12 WM association tracts in each hemisphere. Mean FA illuminates the left AF as a shared tract correlating most significantly with both assessments. Number of fibers and MD capture distinct tracts, revealing the left ILF most strongly correlating with TPVT and the right SLF3 with PERT.

Clinical Implications
Understanding the physical foundations of language and theory of mind will allow neurosurgeons to avoid damaging these integral networks during surgical interventions and will help develop therapeutic sites for those with functional deficits relating to these capacities.
Research Areas
Leo Zekelman*, Fan Zhang*, Daniela Liera, Alexandra Golby, Lauren O’Donnell
Principal Investigator
Alexandra J. Golby, MD

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