title: ERP indices of working memory updating in AD/HD: differential aspects of development, subtype, and medication.
abstract: This study investigated whether children and adolescents diagnosed with the predominantly inattentive and combined subtypes of attention deficit/hyperactivity disorder (AD/HD-in and AD/HD-com, respectively) differed on psychophysiological indices of working memory updating off- and on-stimulant medication, as compared with control subjects and each other. ERPs were recorded in AD/HD and control participants during a one-back working memory task. The N100 (discrimination), P150 (selection), N300 (memory retrieval), and P450wm (updating) components after nontarget stimuli, which served to update working memory with target identity, were assessed. Premedication abnormalities were obtained for the N300 component, delayed in the child AD/HD-com group, and attenuated in the adolescent AD/HD-in group and P450wm component for all AD/HD groups, expressed as either delayed latency and/or attenuated amplitude. ERP abnormalities were predominantly ameliorated after stimulant medication. There were no psychophysiological differences between the subtypes. A general feature of the disorder relates to a deficit in the conscious updating of working memory systems with newly relevant information (P450wm), which varies with age and subtype. Children with AD/HD-com and adolescents with AD/HD-in also exhibit abnormalities in the retrieval of relevant prior memories (N300). This study indicates that AD/HD is related to abnormalities in the capacity to modulate the content of working memory stores.
authors.affiliation: Cognitive Neuroscience Laboratory, Flinders University, SA, Australia.
authors.forename: Hannah A D
authors.initials: HA
authors.lastname: Keage
authors.forename: C Richard
authors.initials: CR
authors.lastname: Clark
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Hermens
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Williams
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kohn
authors.forename: Simon
authors.initials: S
authors.lastname: Clarke
authors.forename: Christopher
authors.initials: C
authors.lastname: Lamb
authors.forename: David
authors.initials: D
authors.lastname: Crewther
authors.forename: Evian
authors.initials: E
authors.lastname: Gordon
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy / Q000503:physiopathology*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology
chemical_list: D000697:Central Nervous System Stimulants