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Papoutselou, Efstratia (2023) Exploring neural markers of language processing using fNIRS in typically developed children and children with Developmental Language Disorder. PhD thesis, University of Nottingham.

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Abstract

Background: Developmental language disorder (DLD) is a life-long condition with no clear biological causes that affects approximately 8% of the population. The diagnosis currently relies on behavioural testing that is not reliably performed on children younger than school age. Consequently, the diagnosis and treatment of DLD is often delayed until after children enter formal education. Early work in the field suggests that neural markers of language processing could be used to develop an objective diagnostic tool that will allow for accurate and early identification of DLD in preschool years and thus access to early interventions. Here we propose the use of a novel non-invasive neuroimaging technique called functional near infrared spectroscopy (fNIRS) to identify neural markers of language processing in children with DLD. Additionally, we argue that to understand atypical language processing, it is imperative to also investigate typical cortical activations in response to language processing to establish the developmental trajectories of the language network. Parallel to these studies we also investigate patterns of neural synchrony during parent-child interactions. Speech and language development in children is thought to rely on successful parent-child interactions, however, little is known regarding the underlying neural mechanisms from which they arise.

Methods: Cross-Sectional fNIRS Studies: A total of 36 participants aged 6–16-year-old (1 participant with DLD) were recruited in two cross-sectional fNIRS studies. Participants underwent a 10-minute resting state imaging session and completed a series of computer-administered language and cognitive tasks while their brain activity was recorded using fNIRS from the bilateral inferior frontal gyrus (IFG) and the bilateral auditory cortices. Hyperscanning fNIRS Study: 12 children aged between 3 and 5 years old and their mothers participated in this study. Neural synchrony in mother-child dyads was measured bilaterally over frontal and temporal areas using fNIRS whilst the dyads were asked to play together (interactive condition) and separately (independent condition). Communication patterns were captured via video recordings and conversational turns were coded.

Survey Study: 43 parents of children with DLD and 44 clinicians with DLD expertise completed a qualitative online survey detailing their views, concerns and recommendations regarding the use of neuroimaging-based tool for the diagnosis and monitoring of DLD.

Results: Cross sectional fNIRS studies: In typically developed children and adolescents, widespread connections between the language regions and the right IFG appear to continue decreasing as age increases. In contrast connections between temporal regions are well established by late childhood. Increased activity over right auditory regions is associated with decreased language skills. Whilst data from the DLD participant is described, further analysis was not possible due to the limited sample size (n=1). Hyperscanning fNIRS study: We successfully recorded inter-brain synchrony in bilateral prefrontal and temporal cortices in mother-child dyads while they engaged in cooperative and independent play. Compared to the independent condition, mother-child dyads showed increased neural synchrony in the interactive condition across the prefrontal cortex and temporo-parietal junction. There was no significant relationship found between neural synchrony and turn-taking, but neural synchrony was negatively correlated with the child’s levels of surgency.

Survey study: Clinicians and parents perceived that a potential tool that could diagnose children with DLD earlier would positively impact the children as it would allow them to access interventions earlier. This study offered a unique account of the factors to be considered in the design and implementation of clinical measures for language disorders from the viewpoints of parents and language professionals.

Conclusions: Overall, this research aimed to identify neural markers of language processing in children with DLD and typically developed children to help develop an objective early diagnostic tool. Ultimately, this research might help maximize the benefits of speech and language therapies to improve the quality of life for children with DLD. This can be very impactful translational research in language development given that currently no objective neural-based tools exist for DLD.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Hartley, Douglas Wiggins, Ian
Keywords:	Developmental language disorder; Neural markers; Neuroimaging; Language processing
Subjects:	W Medicine and related subjects (NLM Classification) > WL Nervous system
Faculties/Schools:	UK Campuses > Faculty of Medicine and Health Sciences > School of Medicine
Item ID:	76238
Depositing User:	Papoutselou, Efstratia
Date Deposited:	13 Dec 2023 04:40
Last Modified:	13 Dec 2023 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/76238

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