4 YEAR PhD IN NEUROSCIENCE
Department of Neuroscience, Physiology & Pharmacology
The Development of Cortical Pain Processing
Pain is essential for survival and human infants display robust behavioural reflex responses to noxious stimulation from birth. What is less clear is how and when this information is processed in the infant brain. Our lab aims to understand the functional maturation of cortical areas responsible for discriminating noxious events and creating the uniquely unpleasant quality of pain.
Our group was the first to discover that noxious stimuli were processed in the human infant brain, using near-infrared spectroscopy (NIRS)1 and time-locked EEG recordings2 to reveal nociceptive event related potentials (nERPs) in response to clinically-essential noxious heel lance. We have also identified the developmental origins of these modality-specific, localized nERPs and shown how they emerge from immature nonspecific, evenly dispersed neuronal bursts to evoked potentials at 35 weeks gestational age3.
While nERPs are an important indication of nociceptive brain activity, they cannot be considered as a final signature of pain. Time-frequency analysis can be used to reveal event related activity patterns in the infant cortex, not all of which are phase-locked to the stimulus and which are therefore not visible on the time average4. Furthermore, in adults, while the first discriminatory stage of cortical pain takes place in the somatosensory cortex it appears that sensory stimuli are only consciously detected when further processed in feed forward-feedback loops between cortical areas; causal modelling could be used to map the development of these networks in infancy. Equally important is the ability to spatially localise an injury upon the body surface5, but nothing is known about the development of somatosensory cortical maps in infants.
To map the developmental trajectory of somatosensory and nociceptive cortical activity patterns and their topographic organisation in human infants using advanced analysis of EEG activity following tactile and pain stimulation.
1. Slater R & Fitzgerald M. Cortical pain responses in human infants. J. Neurosci. 26, 3662–3666 (2006).
2. Slater R, Worley A, Fabrizi L, Roberts S, Meek J, Boyd S, Fitzgerald M. Evoked potentials generated by noxious stimulation in the human infant brain. Eur. J. Pain 14, 321–326 (2010).
3. Fabrizi L, Slater R, Worley A, Meek J, Boyd S, Olhede S, Fitzgerald M. A shift in sensory processing that enables the developing human brain to discriminate touch from pain. Curr. Biol. 21, 1552–1558 (2011).
4. Fabrizi L, Williams G, Lee A, Meek J, Slater R, Olhede S, Fitzgerald M. Cortical activity evoked by an acute painful tissue-damaging stimulus in healthy adult volunteers. J. Neurophysiol. 109, 2393-403 (2013).
5. Cornelissen L, Fabrizi L, Patten D, Worley A, Meek J, Boyd S, Slater R, Fitzgerald M. Postnatal temporal, spatial and modality tuning of nociceptive cutaneous flexion reflexes in human Infants PloS One (in press) (2013)