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Oades, R. D., Wild-Wall, N.,
& Juran, S., (2005).
Fronto-cingular mechanisms, development
and mismatch processes in normal subjects and patients with ADHD growing
up: cognitive ERPs and anatomy.
Australian Journal of Psychology, in press. (Proceedings
of the Australian Society for Psychophysiology, Melbourne,
Dec. 2004)
Introduction: ADHD
problems begin in early childhood and manifest sooner or later with
difficulties in selective information processing. But there is a poor
understanding of the maturation of anatomical bases and the neurobiology
of the processes through adolescence to adulthood.
Three negative-going ERPs
reflecting automatic attentional mechanisms and the threshold to controlled
processing are taken as markers to illustrate the development and the
process.
Results:
a) Mismatch negativity
(MMN), a measure of auditory change detection,
proves to be a marker of early anomalous asymmetric development in frontal
regions in ADHD subjects. Brain electrical source analysis suggests
that changes of frontal and cingulate dipole sources may be expected
normally into the third decade of life. .
b) The N2
component, sensitive to the categorization of stimulus-type, has a poorly
expressed frontal topography after imperative stop-signals in subjects
with ADHD independent of response success. .
c) Indeed, the error-related
negativity (Ne) associated with mistakes
is poorly expressed in ADHD subjects. Ne sources like those for MMN
implicate inferior-mid frontal and mid-cingulate locations - regions
subject to maturation at puberty, and beyond in young "adults"..
Conclusions: Functionally,
in childhood ADHD, the interaction of these regions in “pre-executive”
processing seems impaired (responsiveness to deviance, significance
and feedback). But studies of older ADHD subjects should note that there
is a potential for the putative 'maturation-lag'
of the mediating structures continuing into young adulthood.
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