Dipole source localization of event-related brain activity indicative of an early visual selective attention deficit in ADHD children.
OBJECTIVE
This study was aimed at investigating whether attention-deficit hyperactivity disorder (ADHD) children suffer from specific early selective attention deficits in the visual modality with the aid of event-related brain potentials (ERPs). Furthermore, brain source localization was applied to identify brain areas underlying possible deficits in selective visual processing in ADHD children.


METHODS
A two-channel visual color selection task was administered to 18 ADHD and 18 control subjects in the age range of 7-13 years and ERP activity was derived from 30 electrodes.


RESULTS
ADHD children exhibited lower perceptual sensitivity scores resulting in poorer target selection. The ERP data suggested an early selective-attention deficit as manifested in smaller frontal positive activity (frontal selection positivity; FSP) in ADHD children around 200 ms whereas later occipital and fronto-central negative activity (OSN and N2b; 200-400 ms latency) appeared to be unaffected. Source localization explained the FSP by posterior-medial equivalent dipoles in control subjects, which may reflect the contribution of numerous surrounding areas.


CONCLUSIONS
ADHD children have problems with selective visual processing that might be caused by a specific early filtering deficit (absent FSP) occurring around 200 ms. The neural sources underlying these problems have to be further identified. Source localization also suggested abnormalities in the 200-400 ms time range, pertaining to the distribution of attention-modulated activity in lateral frontal areas.
Jonkman
L M
LM
Department of Neurocognition, Faculty of Psychology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands. l.jonkman@psychology.unimaas.nl
Kenemans
J L
JL
Kemner
C
C
Verbaten
M N
MN
van Engeland
H
H
D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D001931:Brain Mapping; D002648:Child; D002652:Child Behavior; D004569:Electroencephalography; D004585:Electrooculography; D005074:Evoked Potentials, Visual; D006801:Humans; D008959:Models, Neurological; D011930:Reaction Time; D013997:Time Factors; D014796:Visual Perception