Attention Deficit Hyperactivity Disorder T. FISHER, H. PRATT and J. AHARON Evoked Potentials Laboratory Technion-Israel Institute of Technology, Haifa, Israel
The three main symptoms of ADHD Inattention Impulsivity Hyperactivity
What are the brain processes associated with the behavioral impulsivity symptoms?
Subjects 14 subjects diagnosed with Attention Deficit and Hyperactivity disorder. 14 healthy control subjects matched for age and gender Age range: No co-morbidity of psychiatric, neurological or learning disabilities. All subjects were free of medication.
Procedure Stimuli: 2 binaural tones: 1000 Hz (NO-GO) 2000 Hz (GO) 60 dBnHL for 40 ms. Inter-trial interval: 1000 to 2000 ms Task: To GO trials: press button to stimuli. Probability: 80%. To NO-GO trials: inhibit the response. Probability: 20%.
GO NO-GO Behavioral Results
Electrophysiological results grand average, 28 subjects, midline electrodes µV 300Msec Control subjectsADHD subjects GO NO-GO P3 N2 P3 N2 P3 N2
ADHD vs. CTRL in NO-GO Trials CTRL ADHD µV 300Msec
Control > ADHD LORETA images of Control – ADHD difference ADHD Control µV 300msec No go, significant voxels, P< msec stimulus R. Inf. frontal gyrus BA 9, 44,45
Posterior Cingulate BA 23,29,30,31 LORETA images of significant T values ADHD Control µV 300Msec No go, significant voxels, P< Msec stimulus Control > ADHD
Conclusions The ADHD deficit is in stimulus-related processing, not at the perceptual level. ADHD show abnormal activity in brain regions attributed to response inhibition and conflict monitoring.
CTRL N2 ADHD N2 N2
ADHD P3 CTRL P3