"As science continues to shed light on the secret life of the unborn child, a U.K. study has found that babies appear to distinguish painful stimuli as different from general touch from around 35-37 weeks gestation – just before an infant would normally be born.
“We are asking a fundamental question about human development in this study - when do babies start to distinguish between sensations?” said Dr Lorenzo Fabrizi, from University College London, who led the study, A Shift in Sensory Processing that Enables the Developing Human Brain to Discriminate Touch from Pain, which was recently published in the journal Current Biology.
The scientists looked at the brain activity of 46 babies at the University College Hospital Elizabeth Garrett Anderson Wing. Twenty-one babies in the study were born prematurely, giving scientists the opportunity to measure activity at different stages of human brain development, from babies at just 28 weeks of development through to those born ‘full term’ at 37 weeks.
Using electroencephalography (EEG), the scientists measured the babies’ electrical brain activity when they were undergoing a routine heel lance – a standard procedure essential to collect blood samples for clinical use.
In the premature babies the EEG recorded a response to the heel lance of non-specific ‘neuronal bursts’ – general bursts of electrical activity in the brain. After 35-37 weeks the babies’ response changed to localized activity in specific areas of the brain, which the researchers said indicated that they were now perceiving painful stimulation as separate to touch...."
