IMFAR, May 2005

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IMFAR, May 2005

• GAZE-FIXATION AND BRAIN ACTIVATION IN UNAFFECTED
  SIBLINGS OF INDIVIDUALS WITH AUTISM.

Kim M. Dalton, Brendon M. Nacewicz, Emilia
McAuliff,Matt Nersesian, Micah Long, Andrew
L. Alexander Richard J. Davidson. Waisman
Laboratory for Brain Imaging Behavior
University of Wisconsin - Madison
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Theoretical Perspective Brain Function in
Autism.
Specific Aim To better understand the neural
circuitry associated with social/emotion
processes and how abnormalities in these circuits
may be related to social/emotional
differences/deficits in developmental
disabilities such as autism. Specifically
deficits in face processing and gaze-fixation.
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Human Face Processing and Gaze-Fixation in Autism.

• Deficits in attention, learning discrimination
  of human faces, (Osterling, Dawson Munson,
  2002 Joseph Tager-Flusberg, 1997).

• Disproportionate attention to the mouth versus
  eyes, (Klin et al., 2002 Schultz et al., 2002).

• More detailed, less specialized rather than a
  more specialized configural process, (Joseph
  Tanaka, 2003).

• Tendency not to show the face inversion effect,
  (Hobson, Ouston Lee, 1998 Joseph Tanaka,
  2003)

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Previous Studies on Face Processing and
Gaze-Fixation
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Study Designs
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Group differences in feature fixations.
Study I
Study II
Control Autism t-tests Face t(1,19) Mouth
t(1,19) Eyes t(1,19) 1.82, p .04
Control Autism t-tests Face t(1,28) Mouth
t(1,28) Eyes t(1,28) 2.51, p .03
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Study I Control minus autism t-tests. Orange
indicates control gt autism Blue indicates autism
gt control.
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Study II Control minus autism t-tests.
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Clusters in the left amygdala associated with
group differences in Activation as a function of
eye-fixation within subjects.
Study I
Study II
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Sibling Participants Matched on age and IQ
Control n12 (2 female) age 14.3 years (3.62
SD) Autism n12 (4 female) age 14.5 years
(14.16 SD) Sibling n10 (3 female) age 13.10
years (14.9 SD)
WRIT (standardized M 100, SD 15)
SCQ (range 0-40)
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Performance and Judgment Time

• No group differences in judgment time.
• Both the Control Sibling group had faster
  response times for the people vs. objects.
• Control, t(1,11) 3.52, p .005
• Sibling, t(1,9) 3.02, p .01
• Autism, t(1,11) 1.18, p .26
• The Autism group performed less well for the
  people vs. the objects.
• Control, t(1,11) 0.43, p .67
• Sibling, t(1,9) 2.00, p .08
• Autism, t(1,11) 2.50, p .03

ms
correct (out of 10 trials)
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Average Feature-Fixation Time
The Autism and Sibling groups spent less time
fixating the eyes compared to the Control
group. Control Autism t(1,22) 2.20, p
.038 Control Sibling t(1,20) 2.41, p
.025 Autism Sibling t(1,20) 0.24, p .81
ms
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Group ME for people Right fusiform
signal change
Control Autism t(1,22) 4.70, p
.0001 Control Sibling t(1,20) 4.66, p
.002 Sibling Autism t(1,20) 1.07, p .29
signal change
time from stimulus onset (s)
Averaged MR signal time series
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Group Effect for People Right Amygdala
signal change
Control Autism t(1,19) -3.07, p
.006 Control Sibling t(1,17) 0.25, p
.80 Sibling Autism t(1,20) -3.37, p .003
signal change
time from stimulus onset (s)
Averaged MR signal time series
Averaged MR signal time series
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Brain activation as a function of gaze-fixation
signal change
Autism - Control, t(1,22) 2.14, p .04 Autism
Sibling, t(1,19) 2.82, p .01 Sibling -
Control, t(1,19) .96, p .35
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Group differences in amygdala volume

• Nine non-autistic siblings of autistic
  individuals
• Nine age-matched controls
• Nine age-matched autistic individuals
• Group differences in total amygdala volume after
  effects of age and total brain volume are removed.

Mean amygdala volume (mm3)
Control - Autism, t(1,16) ??, p ?? Control -
Sibling, t(1,16) 2.26, p .037 Sibling -
Autism, t(1,16) ??, p ??
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Summary of Findings

• Individuals with ASD display diminished
  gaze-fixation to both familiar and unfamiliar
  faces.
• Individuals with ASD also show diminished
  bilateral fusiform activation and heightened
  amygdala activation to both familiar and
  unfamiliar faces.
• Unaffected siblings of individuals with ASD also
  show diminished gaze-fixation to both familiar
  and unfamiliar faces along with decreased
  fusiform activation but NOT heightened amygdala
  activation.

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Follow-up Research

• More extensive behavioral/cognitive assessment of
  siblings including ADOS.
• Genetics... focusing on amygdala specific gene
  expression.

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Funding Sources.
NICHD Post-Doctoral Training Grant Waisman Core
Grant Leonard Abbeduto Marsha Seltzer NIH
STAART Grant Helen Tager-Flusberg Richard
Davidson NARSAD Grant Richard Davidson
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University of Wisconsin - Madison
Waisman Center Marsha Seltzer
Leonard Abbeduto Morton Ann Gernsbacher
Hill Goldsmith
Waisman Laboratory for Brain Imaging
Behavior Richard Davidson Andrew
Alexander Michael Anderle Donna Cole Ronald
Fisher Andrew Fox Larry Greischar Wil
Irwin Tom Johnstone Daniel Kelley Micah Long
Emilia McAuliff Andrea
McDuffie Brendon Nacewicz Matthew
Nersesian Terrance Oakes Hillary Schaefer
Carien VanReekum Zachary Zugin