Unborn babies can distinguish between pain and general touch from about 35 weeks’ gestation, new research has suggested.
The conclusion follows examinations of the brain activities of premature and full-term babies in a London hospital.
Using electroencephalography (EEG), scientists measured the brain activity of 46 babies at the University College Hospital Elizabeth Garrett Anderson Wing, London, UK, 21 of whom were premature, when they underwent a routine heel lance, which is a standard procedure essential to collect blood samples.
In the premature babies the EEG recorded a response of non-specific “neuronal bursts”.
But about 35-37 weeks, the babies’ response changed to localised activity in specific areas of the brain, which suggested they felt pain differently from touch.
These findings, published online in the journal Current Biology, add to previous studies that show a similar change in the visual system at about 35-37 weeks.
Dr Rebeccah Slater, UCL Neuroscience, Physiology and Pharmacology, said: “Premature babies who are younger than 35 weeks have similar brain responses when they experience touch or pain. After this time there is a gradual change, rather than a sudden shift, when the brain starts to process the two types of stimuli in a distinct manner.”
Dr Lorenzo Fabrizi, lead author of the paper from UCL Neuroscience, Physiology and Pharmacology, said: “We are asking a fundamental question about human development in this study: when do babies start to distinguish between sensations?”
A shift in sensory processing which enables the developing human brain to discriminate touch from pain. Current Biology September 2011
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