1. ATTENTION DEFICIT

7. Theories of ADHD Deficits not in information processing or in Perceiving information. Observed Deficits: –Motor Inhibition –Control –Anticipating Events

8. Current Theoretical Focus Central Deficit of Disorder: –Failures of Inhibition The capacity to inhibit learned responses Creating or maintaining a delay in responding to an event. The capacity to fluidly interrupt ongoing responses due to performance feedback. The ability to delay or refrain from responding due to environmental cues.

9. Secondary Effects? Impaired motivational or reward systems. (particularly evident in ADHD inattentive subtype) –Exhibition of a shorter and steeper delay of reinforcement gradient. –Preference of small, immediate reward vs. delayed gratification. –Greater frustration on a partial reinforcement schedule. –(Treatment: low dose stimulants)

10. Proposed Etiology Reduced DA release in Nucleus Accumbens Decreased Cortical AcH function –Increase in Smoking in ADHD Increased Cortical Noradrenergic Function –Increase in symptomatology under conditions of stress. Alternative: Changes in Ach at level of brainstem may be altering DA and NE.

11. Supporting Evidence Neuroimaging – anatomical changes in globus pallidus and frontal cortex Reduced striatal activity during performance of inhibition tasks. Reduced Noradrenergic activity, altered DA reuptake, changes in the D4 receptor. Genes: DAT1 and DRD4 – higher rates of the 7 repeat allele in DRD4.

12. Questions: What is happening to NE regulation? Is ACH system dysfunctional? What is happening to ACH and NE receptors?