Thalamocortical Connectivity in Autism S

Thalamocortical Connectivity
In Autism Spectrum Disorder
- An fcMRI and DTI Tractography
Study

Aarti Nair1,2, Dinesh K. Shukla1, Jeff M.Treiber1,
Brandon Keehn1, Ralph-Axel Müller1,2,3
Brain Development Imaging Lab, Dept. of Psychology, SDSU
2
Joint Doctoral Program in Clinical Psychology, SDSU/UCSD
3
Dept. of Cognitive Science, UCSD

1

Background
Thalamus


Important subcortical relay structure
sensory, motor, and attentional nuclei

Thalamocortical connectivity laid out during
neuronal migration along radial glial cells

(Rakic et

al. 2004)

Functional differentiation and development of
columnar architecture in cerebral cortex

(O’Leary &

Nakagawa 2002)

Highly specific patterns of thalamocortical
connectivity
al. 2008, 2010)

(Behrens et al., 2003, Fair et al. 2010, Zhang et

Thalamus in ASD
Thalamic abnormalities in ASD
Reductions in volume (Tsatsanis et al. 2003), neuronal
integrity

(Friedman et al 2003),
(Haznedar et al. 2006)

and glucose metabolism

Abnormal serotonin synthesis along cerebellothalamo-cortical pathway

(Chugani et al. 1997)

Minicolumnar abnormalities (Casanova et al. 2006) –
Early-onset anomalies of thalamocortical
connectivity

Objective

Assess functional connectivity and white matter
integrity between five different cortical regions of
interest (ROIs) and thalamus in adolescents with
ASD compared to TD adolescents

Cortical ROIs based on Zhang et al.(2008)
prefrontal, motor, somatosensory, temporal, and
parietal-occipital cortex
(Zhang et al. 2008)

Participants
TD (n=22)

ASD (n=18)

2 left-handed; 3 female

2 left-handed; 2 female

Mean

Range

SD

Mean

Range

SD

p

Age

14.5

12.1–
16.8

1.5

14.3

12.1-17.1

1.6

.51

IQ

109

88-126

10.7

114

87-141

14.1

.30

 Participants aged 12-17 years
 No significant age, IQ, sex, handedness
differences
 ASD diagnosed using DSM-IV, ADOS and ADI-R

Data acquisition
GE 3T aMR750 scanner with 8-channel head coil
Anatomical
 FSPGR T1-weighted sequence (180 slices; 1mm3 resolution)

BOLD (fcMRI)
 6-minute resting-state functional EPI (180 whole-brain
volumes,TR: 2000ms; TE: 30ms; 3.4mm slice thickness; inplane resolution 3.4mm2)

DTI
 Single-shot diffusion-weighted EPI (TR=5000 ms, TE=99.4ms,
2mm slice thickness)
 Two degrees of diffusion weighting (b = 0 and 1000 s/mm2; 61
directions)

Methods
ROIs based on Brodmann areas identified using
Talairach-Tournoux Stereotaxic Atlas (AFNI; TTDaemon)

Boundaries taken from previous studies of
thalamocortical connectivity

(Zhang et al., 2008; Fair et al.,

2010, Zhang et al., 2010)

Thalamus mask obtained from TT atlas

Methods: fcMRI

FcMRI analysis using Analysis of Functional
NeuroImages (AFNI; Cox, 1996)
 Physiological regression (heart beat, respiration)
 Field map correction
 Motion correction and co-registration to anatomical image
 Normalization to Talairach space
 Spatial smoothing (4mm Gaussian kernal)
 Band-pass filtering (.008