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 Controlling Saccadic Eye Movements Posterior parietal cortex Dorsolateral Prefrontal cortex Supplementary Eye Field Frontal Eye Field Cerebellum Visual Cortex Brainstem Reticular Formation Basal Ganglia Superior Colliculus

Visual Cortex LGN Retina Thalamus CN SNr STN GPe Basal Ganglia Parietal Cortex (LIP) DLPFC SEF FEF Frontal Cortex RF Saccade Cerebellum SCs SCi Neural Circuitry Controlling Saccade Production

Pro-Saccade Task Anti-Saccade Task Stimulus-response compatibilityStimulus-response incompatibility Respond automaticallyVoluntary response: extra stages of processing 1) suppress automatic response 2) transform (invert) target vector

Pro-Saccade Task Anti-Saccade Task FP T T Gap Condition Overlap Condition

Munoz and Everling, Nature Reviews in Neuroscience 5 (2004)

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 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

Preliminary Results Performance of female FAS participants and age-matched controls