Widespread nociceptive maps in the human neonatal somatosensory cortex

Abstract

Topographic cortical maps are essential for spatial localisation of sensory stimulation and generation of appropriate task-related motor responses. Somatosensation and nociception are finely mapped and aligned in the adult somatosensory (S1) cortex, but in infancy, when pain behaviour is disorganised and poorly directed, nociceptive maps may be less refined. We compared the topographic pattern of S1 activation following noxious (clinically required heel lance) and innocuous (touch) mechanical stimulation of the same skin region in newborn infants (n=32) using multi-optode functional near-infrared spectroscopy (fNIRS). Within S1 cortex, touch and lance of the heel elicit localised, partially overlapping increases in oxygenated haemoglobin concentration (D[HbO]), but while touch activation was restricted to the heel area, lance activation extended into cortical hand regions. The data reveals a widespread cortical nociceptive map in infant S1, consistent with their poorly directed pain behaviour.

Early structural connectivity within the sensorimotor network: Deviations related to prematurity and association to neurodevelopmental outcome

“…In this study, we hypothesized that WM microstructure within SM tracts would show a significant maturational delay at TEA in PT infants compared to FT neonates, with distinct patterns as a function of GA at birth and across corticosubcortical and cortico-cortical tracts. This was based on the assumption that early peripheral stimuli are essential for the emerging SM network maturation, and that preterm birth is associated with modified SM stimuli and experiences, notably related to numerous and various procedures in NICU (Mörelius et al, 2006;Gibbins et al, 2008), which might have a differential effect on somatosensory and motor systems (Duerden et al, 2018;Schneider et al, 2018;Jones et al, 2022). Of direct relevance, previous studies have reported either higher tactile sensitivity in PT infants at TEA (André et al, 2020), tactile hyporeactivity, lower brain responses (Maitre et al, 2017) and/or undifferentiated integration of nociceptive versus nonnociceptive stimuli (Fabrizi et al, 2011), in association with WM abnormalities (Brummelte et al, 2012;Zwicker et al, 2013).…”

Tactile sensitivity and motor coordination in infancy: Effect of age, prior surgery, anaesthesia & critical illness

“…Such changes include a decrease in both tonic background activity and in muscle response to passive joint movement with increasing age, which may be attributable to a reduction of the sensitivity of motor units due to spinal and supraspinal reorganisation [49,50]. Poorly directed pain behaviour is consistent with widespread nociceptive maps in the human neonatal somatosensory cortex [51].…”

Early structural connectivity within the sensorimotor network: deviations related to prematurity and association to neurodevelopmental outcome

“…In this study, we hypothesized that the SM tracts would show a significant maturational delay in PT compared to FT neonates, with distinct patterns as a function of GA at birth and across cortico-subcortical and cortico- cortical tracts. This was based on the assumption that early peripheral stimuli are essential for the emerging SM network maturation, and that premature birth is associated with modified SM stimuli and experiences (notably related to numerous and various procedures in NICU (Mörelius et al, 2006; Gibbins et al, 2008), which might have a differential effect on somatosensory and motor systems (Duerden et al, 2018; Schneider et al, 2018; Jones et al, 2022). Of note, previous studies have reported either higher tactile sensitivity in PT infants at TEA (André et al, 2020), tactile hyporeactivity and/or undifferentiated integration of nociceptive versus non-nociceptive stimuli (Fabrizi et al, 2011), in association with some WM abnormalities (Brummelte et al, 2012; Zwicker et al, 2013).…”