Saccadic Eye Movements: A New Diagnostic Tool with Eye-Opening Possibilities for FAS Research James...
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Transcript of Saccadic Eye Movements: A New Diagnostic Tool with Eye-Opening Possibilities for FAS Research James...
Saccadic Eye Movements: A New Diagnostic Tool with Eye-Opening
Possibilities for FAS Research
James N. Reynolds
Department of Pharmacology & Toxicology,Centre for Neuroscience Studies,
Queen’s University,Kingston, Ontario, Canada
Saccadic Eye Movements: Integration of activity across multiple neural circuits
• Executive Control: ability to control behaviour flexibly– Responding automatically to a stimulus in one
set of circumstances– Suppressing the automatic response in favour
of an alternative in a different situation
Saccadic Eye Movements: Developmental regulation of the ability to perform the anti-
saccade task
• Young children (< 8 years of age) have difficulty suppressing the automatic pro-saccade– Not due to difficulty understanding the task
• Suppression ability develops gradually in school age children– Adult performance levels at around 18 years of age
• Attributed to protracted maturation of the frontal lobes into the second decade of life
• Improved inhibitory control over the saccade-generating circuitry (plasticity)
Multiple Brain Areas Involved in ControllingSaccadic Eye Movements
Posterior parietal cortexDorsolateralPrefrontal cortex
SupplementaryEye Field
Frontal Eye Field
Cerebellum
Visual Cortex
BrainstemReticular Formation
Basal Ganglia
Superior Colliculus
Visual Cortex
LGN
Retina
ThalamusCN
SNr
STN
GPe
Basal Ganglia
Parietal Cortex (LIP)
DLPFC
SEF
FEF
Frontal Cortex
RF Saccade
Cerebellum
SCsSCi
Neural Circuitry Controlling Saccade Production
Pro-Saccade Task Anti-Saccade Task
Stimulus-response compatibility Stimulus-response incompatibility
Respond automatically Voluntary response: extra stages of processing
1) suppress automatic response
2) transform (invert) target vector
Saccadic Eye Movements: Clinical Findings in
Neurodevelopmental/Neurodegenerative Disorders • Attention Deficit Hyperactivity Disorder
– increased error rate in anti-saccade task– no change in reaction time for correct anti-saccades
• Schizophrenia– increased error rate in anti-saccade task– prolonged reaction times for correct anti-saccades
• Parkinson’s Disease– increased error rate in anti-saccade task*– prolonged reaction time for correct anti-saccades
Fetal Alcohol Spectrum Disorders
• Neuropathological and/or functional deficits reported in brain structures involved in saccadic eye movements– Prefrontal cortex, caudate putamen, thalamus, cerebellum
• Neurobehavioural deficits in executive function– e.g., planning, response inhibition, abstract thinking, flexibility
• Hypothesis: Individuals diagnosed with FASD will have specific abnormalities that can be measured with eye movement testing
Pilot Study
• 10-15 Children with a diagnosis of FAS– 8-12 years of age, male and female
• Education History
• Medical History
• Family History
• Conners’ Rating Scales
• Pro-saccade, Anti-saccade task