International Meeting for Autism Research: Microstructural White Matter Properties In Autism Spectrum Conditions: Correlations with Empathy

Microstructural White Matter Properties In Autism Spectrum Conditions: Correlations with Empathy

Friday, May 13, 2011
Elizabeth Ballroom E-F and Lirenta Foyer Level 2 (Manchester Grand Hyatt)
9:00 AM
A. N. Ruigrok1, H. Howells2, M. V. Lombardo1, S. A. Sadek1, G. Pasco1, F. dell'Acqua2, M. C. Lai1, M. Catani2, D. G. Murphy3, U. K. MRC AIMS Consortium4 and S. Baron-Cohen1, (1)Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom, (2)Section of Brain Maturation, Department of Psychological Medicine and Psychiatry, Institute of Psychiatry, King's College London, London, United Kingdom, (3)Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, King's College London, London, United Kingdom, (4)Institute of Psychiatry, King's College London; University of Cambridge; University of Oxford, London, United Kingdom
Background:  Individuals with autism spectrum conditions (ASC) have difficulties with identifying (complex) emotional facial expressions and mentalizing. Several studies using fMRI found decreased activation in areas of the “social brain” in mentalizing and emotion recognition tasks (Baron-Cohen et al., 1999; Deeley et al., 2007). Two white matter fiber tracts, the inferior longitudinal fasciculus (ILF) and the inferior fronto-occipital fasciculus (IFOF) have been found to be involved in face perception by a lesion study (Philippi, Mehta, Grabowski, Adolphs & Rudrauf, 2009) and were associated with age-related changes in face perception (Thomas et al., 2008): reduced structural connectivity of these tracts was correlated with performance on emotion recognition (Philippi et al., 2009) and a face discrimination task (Thomas et al., 2008). Previous diffusion tensor imaging (DTI) studies have revealed reduced fractional anisotropy (FA), and increased mean diffusivity (MD), radial diffusivity (RD), and number of streamlines in the ILF and IFOF of individuals with ASC (Pugliese et al., 2009; Bloemen et al., 2010; Shukla, Keehn & Muller, 2010). Building on these prior findings, the present study will investigate if there is a relation between microstructural properties in these tracts and performance on two empathy measures: the “Reading the Mind in the Eyes” Test (Eyes) and with the Empathy Quotient (EQ).

Objectives:  To investigate (1) whether there are any differences in microstructural properties of the IFOF and ILF between adult males with ASC and age and IQ-matched typical control subjects, and (2) if any structural differences found (e.g. in mean FA, MD, RD, and/or number of streamlines) correlate with EQ scores and/or performance on the Eyes Test. It is hypothesized that individuals with ASC will perform worse on the Eyes test and have lower scores on the EQ than the typical controls. Furthermore, it is predicted that reduced connectivity is correlated with performance on the Eyes and EQ.

Methods:  Data from 30 males with a clinical diagnosis of ASC and 30 typical developed males who participated in a multi-center study and met the cut-off criteria of autism from the Autism Diagnostic Interview-Revised (ADI-R) were analyzed. Data preprocessing (e.g. eddy current correction with rotation of the b matrix, diffusion tensor estimation using a nonlinear least-squares algorithm and whole brain tractography using Euler Integration) was executed using ExploreDTI (Leemans, Jeurissen, Sijbers & Jones, 2009). Dissections of the ILF and IFOF were performed according to guidelines given by Catani & Thiebaut de Schotten (2008) using TrackVis (Ruopeng Wang & Wedeen, J. Van,, Martinos Center for Biomedical Imaging, Massachusetts General Hospital). Furthermore, all participants completed the EQ and Eyes test.

Results:  The groups were matched on age (between 18 and 45 years) and IQ. Group differences were found on EQ (t=8.2, p<.001) and Eyes (t=3.8, p<.001) measures. Tractography and correlational results will be presented on the poster.

Conclusions:  The results are discussed in relation to previous reported abnormalities in structural connectivity of individuals with ASC and how this may relate to reduced performance on empathy tasks.

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