Transcript ClassPresentation07

GAZE FIXATION AND THE
NEURAL CIRCUITRY OF FACE
PROCESSING IN AUTISM
Sakina Dharsee
Psychology - 260
Introduction
• Autism: Developmental disorder, unique profile of social and
emotional behavior.
• Symptomatology: Diminished gaze fixation, lack of social or
emotional reciprocity.
Previous research: Fusiform
gyrus less activated in autistic
patients.
Deficit: Which circuits are highly
activated compared to normal?
Hypothesis
• Fusiform gyrus hypoactivation - Less time fixating on eye
regions: Cause or consequence?
• Hyperactivation in amygdala (region responsible for
processing threatening, social and emotional cues)
Experimental Task
Stimulation: Mock-up of MRI scanner.
MRI Scan
Eye movement: Eye-tracking device.
Study 1:
• 14 autistic males (M:15.9, SD: 4.71)
• 12 normal males (M: 17.1, SD: 2.78)
• Task: Is the picture emotional or neutral?
• Half straight, half turned.
Study 2:
• 16 autistic males (M:14.5, SD: 4.60)
• 16 normal males (M: 14.5, SD: 4.56)
• Task: Is the picture familiar to you?
• Ten photographs of family or friends.
Result
Study 1:
Autistic group:
• Longer judgement time for
emotional and straight ahead faces.
• Significantly less time fixating on
eyes.
• More activation in left amygdala.
Control group:
• More activation in bilateral fusiform
gyrus.
a – Right fusiform gyrus
b – Left fusiform gyrus
Study 2:
Control group:
• More activation in bilateral
fusiform gyrus.
Autistic group:
• Significantly less time fixating on
eyes.
• More activation in right
amygdala.
• No differences in judgement
time.
Average duration of fixation on
mouth, eye region and face in
general.
Study 1: g – Left amygdala
Study 2: e – Right amygdala
Discussion
• Individuals with autism scan and process faces differently.
• Deficits in processing emotional cues and in processing
socially engaging faces.
• Greater amygdala activation in autistic group for both
studies.
• Eye fixation creates a negative over-arousal mediated by
the amygdala – diminished gaze fixation reduces this.
Negative over-arousal
Increased sensitivity to
social stimuli
Diminished gaze fixation
Hypoactivation of fusiform gyrus
Strengths and Limitations
Strengths:
• Experimental control.
• Attempt to reduce performance
anxiety.
• Stimulation session.
Limitations:
• Based solely on data
obtained from males.
• Inconsistency.
Future directions:
- Lateralization of amygdala – left for emotion, right for familiarity?
(Baas et al., 2004)
- Treatment research: Can autistic patients be trained to scan and
process faces normally, resulting in normal levels of fusiform gyrus
activation?
Personal Opinion
• Congruent with previous findings, and makes a new discovery.
• Research can contribute towards the treatment and counselling of
autistic children.
• Leads into further research on the disorder – what are the circuits
associated with other symptoms?
Thank You!
Any questions?