1. Attention Deficit Hyperactivity Disorder T. FISHER, H. PRATT and J. AHARON Evoked Potentials Laboratory Technion-Israel Institute of Technology, Haifa, Israel

2. The three main symptoms of ADHD Inattention Impulsivity Hyperactivity

3. What are the brain processes associated with the behavioral impulsivity symptoms?

4. Subjects  14 subjects diagnosed with Attention Deficit and Hyperactivity disorder.  14 healthy control subjects matched for age and gender  Age range: 18-30. No co-morbidity of psychiatric, neurological or learning disabilities.  All subjects were free of medication.

5. 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%.

6. GO NO-GO Behavioral Results

7. Electrophysiological results grand average, 28 subjects, midline electrodes + - 15 µV 300Msec Control subjectsADHD subjects GO NO-GO P3 N2 P3 N2 P3 N2

8. ADHD vs. CTRL in NO-GO Trials CTRL ADHD + - 5 µV 300Msec

9. Control > ADHD LORETA images of Control – ADHD difference ADHD Control + - 15 µV 300msec No go, significant voxels, P<0.05 187- 207 msec stimulus R. Inf. frontal gyrus BA 9, 44,45

10. Posterior Cingulate BA 23,29,30,31 LORETA images of significant T values ADHD Control + - 15 µV 300Msec No go, significant voxels, P<0.05 308-339 Msec stimulus Control > ADHD

11. 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.

12. CTRL N2 ADHD N2 N2

13. ADHD P3 CTRL P3