Development of somatosensation in preterm infants: a neonatal precursor of sensory processing disorders in childhood

About 60,000 infants are born prematurely each year in the UK. Their chances of survival have steadily increased in recent times thanks to better neonatal care, however, there is still not much improvement on their neurodevelopmental outcome. More than 40% of preterm children at school age will have difficulties in handling sensory information which will have a negative impact on their quality of life and make learning, coordination and communication a struggle. Prematurely born children may have exaggerated reactions to a mild stimulus or not respond at all to something painful and they may also have problems in coordinating their movements or balance on a bench. This is because the sensory information that reaches their brain does not get handled correctly. However, we do not know the mechanisms that lead to these issues, how to identify who will develop sensory problems and when to intervene.

Preterm neonates are born during a critical phase of their brain development and are exposed to the external world ahead of time. Many of them can spend their first months of life in neonatal care, where they are exposed to different and more intense stimuli than those normally experienced in the womb. Their premature birth and this experience may affect the way their brain develops and interfere with the maturation of brain circuits that are responsible for processing the external environment. This very early disruption to sensory functions could have a cascading effect on how a child explore and experience their environment, which in turn will lead to the sensory and cognitive challenges suffered by this population. If we could recognise that there is something wrong with sensation and perception at birth, clinician and carers could intervene when the brain circuits are still forming and potentially put them on the right track. The families would also benefit from understanding how their children are developing and how they can support them to improve chances of a good outcome, for example by adapting the sensory environment to the child's functional needs. This would help reduce the emotional, psychological, physical and economic challenges of prematurely born children and their families in the long term.

The overall aim of this project is to understand how sensory information is normally processed by the neonatal brain, how this is affected by premature birth and whether issues in these functions lead to later sensory processing and associated neurodevelopmental disorders. Senses are processed in a ladder-like hierarchy, with the bottom 'rungs' developing early in the womb, while higher rungs develop just before normal birth. Disruption to any of these steps will result in an aberrant perception of the environment and because they develop just before birth, they may be vulnerable to prematurity. We will map the development of the brain functions that allow an individual to filter out unnecessary information and to put together information coming from different senses, and to actively explore the environment. We will then assess whether these functions are more likely to be altered in preterm babies that spent their first weeks of life in hospital care. Finally, we will follow these babies up to 30 months of age when we will be able to test their development and sensory behaviour and see whether brain processing at birth can predict long-term outcomes.
In summary, understanding the development of sensory processing in the neonatal brain will allow carers and families to provide early targeted and individualised interventions to infants at risk of sensory and associated neurodevelopmental disorders. Finally, the results will help policy makers in making decisions regarding funding for health services, considering that neurodevelopmental and cognitive disabilities are associated with high societal costs in terms of educational support and provision of care while the resources that communities can provide to them are limited.

This project aims to understand the mechanisms relating premature birth to later sensory processing and broader neurodevelopmental disorders which are common in preterm born children. We will map the development of (i) passive and (ii) active cortical somatosensory functions over the equivalent of the last trimester of gestation, (iii) assess the effect of premature birth and associated care on these processes and finally (iv) relate these neonatal functions to sensory and cognitive outcomes in childhood. We will define: (a) EEG cortical measures related to stimulus intensity (registration), decrease in response to repeated stimuli (gating), interference with other stimulus (multimodal integration) and (b) the sensorimotor loop associated with active sensing during palmar grasping by measuring the coordination between cortical motor signals (EEG) - muscle activity (EMG) - force (Pressure) - cortical sensory feedback (EEG) in full-term neonates. We will then assess how these change with degree of prematurity in a sample of 110 infants between 28-37 wks postmenstrual age using normative modelling. We will then assess whether these sensory functions are affected by premature birth and associated neonatal care by comparing these measures between a group of 60 preterm neonates at term-equivalent age and 50 full-term controls. The full-term controls will be used to model a normative distribution against which to compare the functions of individual preterm neonates allowing to account for inter-individual variability. Finally, we will longitudinally follow-up these infants with parental questionnaires between 6 and 30 months of corrected age and a comprehensive in-person evaluation at 18 and 30 months to assess trajectories of sensory behaviors and more general psychopathological and developmental outcomes. This will allow us to look for the association between sensory neuronal functions at term (or term-equivalent) age and behavioural manifestations in childhood.