Identifying the neural network abnormalities underlying developmental language disorder

About 7% of children grow up experiencing unexplained difficulty in learning to use language. Their problems cannot be explained by a lack of opportunity, intellectual, visual or hearing impairment, or social deprivation. Difficulties in using and understanding language result in under achievement in education, low self-esteem and reduced employment opportunities. Awareness of language impairments affecting school-age children is lacking in education, in the employment sector, and in society more generally. This contrasts starkly with the public's awareness and understanding of other developmental disorders such as dyslexia, autism and attention deficit disorder. Scientific studies show that language impairments can be caused by genetic abnormalities. However, we know little about the differences in the brain that relate to the language learning difficulties seen in children. We need to improve our understanding of how the brain is organised and how it functions in children with developmental language disorder. In the future, this new knowledge could help us to develop the means to help affected children through designing novel therapies.

Our proposed project will provide us with detailed pictures of the brain's structure and function in children with developmental language disorder. These children will be compared to children of the same age who have experienced normal language development. We will contact children who were previously identified in a separate study and who have a range of language abilities. We will use MRI brain scans to study 160 children aged 10-14 years; 80 with developmental language disorder and 80 without. We will measure their ability to use and understand language, their reading ability and their intelligence. We will also look at their ability to learn sequences of sounds and movements and how this learning differs according to task instructions and feedback.

The research will benefit from using the most up-to-date research MRI brain scanner and new ways of analysing the brain imaging data that are being developed at our centre. Traditionally, scientists have thought of the brain as a series of units where information passes along from one unit to the next as if on factory line. New ways of thinking about the brain view it as a network of areas that send information back and forth in circuits. Our study aims to use sophisticated computational analyses to reveal these networks and determine how they differ according to a child's language abilities.

According to some researchers, children with language learning impairments have problems in one particular learning network that allows us to automate skills and habits, and learn rules. Things learned with this network are often beyond our awareness, such that we cannot readily explain how we know something - like how to ride a bike or the rules of our language. Our research will test this theory by examining how children perform on tests of skill learning and also by looking at the structure and function of the brain areas involved.

One of the problems with studying children with language impairments is that they each experience a slightly different set of problems. Also, patterns of strength and weakness in abilities can alter over the course of development. We will use our brain imaging data to identify the different patterns of impairment across the large group of children studies and relate this to differences in the brains.

We will make the brain imaging data that we collect in this study available to the scientific community. This will allow us to share our data with other groups and ultimately to compare findings across studies and between different developmental disorders e.g. with autism. Also, we will develop new tests using tablets that can be easily used by children of all ages. We will make the tests and the results available to other users via the internet.

Approximately 7% of children experience unexplained difficulties in learning their first language, despite relatively typical development in other domains. Surprisingly little is known about the neural correlates of developmental language disorder.

We will use state-of-the-art methods for acquisition and analysis of brain imaging data and detailed behavioural testing to study a large population of children with a range of language learning abilities. We will recruit eighty children with impairments previously identified in a large study screening school-aged children in Surrey (SCALES study run by project partner Prof. Norbury) and 80 children experiencing typical language development. We aim to provide a detailed characterisation of the structure and function of the brain networks underlying developmental language disorder in these children. We will specifically test two hypotheses, namely that children with developmental language disorders show: (i) structural and functional alterations in corticostriatal circuits; (ii) atypical structural and functional lateralisation. We will relate different measures of the structure and function of neural networks to the various patterns of performance on verbal and nonverbal behavioural measures. These exploratory analyses will inform and extend our existing theoretical frameworks concerning the neural underpinnings of DLD. Finally, we aim to share our data to allow comparison with other neurodevelopmental disorders, such as autism.

The proposed work is important for two reasons: (i) it will enhance our understanding of the specific neural circuits associated with language-learning impairment, and (ii) we will test specific hypotheses about the underlying causal deficit. The findings may also help identify possible routes to intervention and novel therapeutic approaches.

1. Children with developmental language disorder and their families
We believe that the main beneficiaries of this research will be our research participants i.e. children with language impairments and their families. These are the ones who are likely to be most interested in the proposed research and its outcomes and potentially stand to benefit the most from it. We will disseminate the study findings through existing outlets that were created to reach these groups and through a study-specific website. Professors Bishop and Norbury are founding members of RALLI (Raising Awareness of Language Learning Impairments), a YouTube channel that is a resource for children with language impairments and their families. We will continue to use this platform for dissemination of the new study's findings. In general, the study may increase public awareness of language learning impairments and their neural origins.

2. Speech and Language Therapy Community
The work proposed here will shed further light on the underlying brain abnormalities associated with developmental language disorder. It may also inform our understanding of how best to optimize learning in children with impairment. Such an understanding would be of interest to a wider group of beneficiaries, not just the individuals affected, but the therapists and clinical teams that work with children with developmental language disorder and others with communication difficulties. It is likely that a better understanding of language impairment and its therapy will impact the health and wellbeing, and ultimately the quality of life, of affected children. Long-term, the project may contribute to shaping health services for people with communication disorders. There is potential impact for this research to affect evidence-based policy, for example research and clinical policy generated by the Royal College of Speech and Language Therapists (RCSLT). For instance, recent discussions at a meeting (organized by Prof. Bishop) to reach consensus on identifying features and terminology for language impairments in January 2016 centered around the need to build evidence on response to intervention and identify those who would recover spontaneously versus those who would need further intervention. We have therefore incorporated these questions in our study, as planned exploration of neural characteristics is likely to shed some light on these issues.

3. Educators
Similarly, teachers and special needs coordinators may benefit from this research by learning more about the causes of developmental language disorder and raising general awareness of these difficulties. The provision of support within mainstream education may ultimately benefit from demonstration of how language learning is best optimized in children with impairments. Effective strategies for remediation of language learning have the potential to improve quality of life for the affected children and relieve the burden on provision of support in education.

4. ICAN and AFASIC (charities)
We maintain strong links with the charities ICAN and AFASIC, two charities that support parents and children with language and communication disorders. They each provide help and advice to parents, practitioners and educators about speech, language and communication development. These charities are therefore other likely beneficiaries of this research and will aid dissemination of our work to the wider public where it may reach parents of children affected by language impairment who are not involved in the research. This dissemination may increase interest in the charity, which could in turn benefit from public donations.

5. Project research staff
The researchers employed on this project will benefit from further training in developmental cognitive neuroscience. They will learn novel analysis techniques for image analysis. Such training will improve employability and skill transfer in academia and clinical health research.