“These children can often grow up to be either more or less sensitive to pain than usual.”
Could noxious experiences such as ‘heel sticks’ - common in pre-term infant care – disrupt development of their neurological circuits and sometimes prime them for hypersensitivity?
New research to determine when the infant nervous system becomes able to distinguish simple touch from a painful stimulus suggests this might be possible.
The researchers, whose findings were reported Sep 8 in Current Biology,(1) say their study of preterm infants between the ages of 28 and 45 weeks gestation shows that the brain begins to produce distinct responses to a simple touch versus a clinically essential heel lance relatively late in gestation.
Infants can't actually tell you whether something hurts or not, so the investigators relied on recordings of brain activity by electroencephalography (EEG). And, based on their findings, "Babies can distinguish painful stimuli as different from general touch from around 35 to 37 weeks gestation - just before an infant would normally be born," says lead author Lorenzo Fabrizi, PhD, a researcher at University College London. (Babies’ due dates are based on 40 weeks of pregnancy, and babies are generally considered full term at 37 weeks.)
Recent studies have emphasized the importance of bursts of neuronal activity, both spontaneous and evoked, during the formation of functional brain circuitry, the researchers explain. And that “bursting” pattern of activity shifts during development to “adult-like” responses that are more specific to particular sensory inputs.
Implications for Treatment, Care & Development
The results may have implications for the treatment, care, and development of premature newborns, Dr. Fabrizi says, noting that these children can often grow up to be either more or less sensitive to pain than usual.
"Repeated noxious stimulation of the kind used in this study is a feature of neonatal intensive care," the researchers wrote.
"Our finding that noxious heel lance increases neuronal bursting activity in the brain from the earliest age raises the possibility that excess noxious input may disrupt the normal formation of cortical circuits, and that this is a mechanism underlying the long-term neurodevelopmental consequences and altered pain behavior in ex preterm children."
1. Cited article: “A Shift in sensory processing that enables the developing human brain to discriminate touch from pain,” Fabrizi L, et al. Current Biology, Sep 8, 2011
Source: Cell Press news release, Sep 8, 2011