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Hall lab
HallRichardW@uams.edu
Survival of extremely
premature neonates has improved greatly, requiring prolonged neonatal
intensive care that is associated with repetitive pain, stress, and
maternal separation. These infants, however, develop a high prevalence
of cognitive deficits and abnormal behaviors during their early
childhood and school years. Multiple follow-up studies of ex-preterm
children have reported major developmental deficits, with lifetime needs
for special assistance, and increasing burdens on the health care
budget. Early repetitive pain or maternal separation, both occurring
routinely in preterm babies, lead to permanent changes in brainstem and
spinal cord circuitry, neuroendocrine function, or cognition. These
changes are later manifested as abnormal pain processing, increased
anxiety/stress disorders, attention deficit disorder, and other atypical
behaviors.
We
hypothesize that repetitive pain paradigms lead to attention deficit
disorder and poor cognition resulting from an abnormal regulation of
preattentional mechanisms (arousal, sensorimotor gating) in older
children. To examine pre-attentional mechanisms in human adolescents we
have been recording the sleep state-dependent midlatency auditory evoked
P50 potential, as well as attentional processes using a psychomotor
vigilance task. Our results suggest that adolescents who were born
pre-term (PT) become equally segregated into three groups of patients,
one with low P50 potential amplitude (decreased level of arousal- LO),
one with normal level of arousal (MED), and one with exaggerated level
of arousal (hypervigilant- HI). All three groups show marked decreases
in reaction time. These results suggest that both arousal and
attentional deficits are evident in ex-pre-term adolescents. However,
the differential electrophysiological profiles suggest different forms
of therapy may be required. Interestingly, major differences in
habituation to repetitive stimulation were not observed. Moreover, the
changes in P50 potential amplitude were not correlated with weight at
birth or weeks of gestation at birth. This suggests that we may be able
to identify the potential direction of benefits in order to tailor
treatment.

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