Functional MRI Study of the Involvement of Cortico-cerebellar and Cortico-striatal Networks in Children With a Developmental Coordination Disorder (DCD) and/or Developmental Dyslexia (DD)
Functional MRI Study of the Involvement of Cortico-cerebellar and Cortico-striatal Networks in Children With a Developmental Coordination Disorder (DCD) and/or Developmental Dyslexia (DD)
All the studies underlined the high frequency of co-morbid associations in specific learning disorders. Understanding the reasons for these associations could enable us to determine the cerebral bases that underlie each disorder. Their frequent association suggests the etiological bases are partly common, it seems logical to turn to explanatory models of various common specific disorders. The model recently proposed by Nicholson & Fawcett (2007) suggests a specific disorder of procedural learning. But the brain networks involved in this learning could be achieved separately. We intend therefore to study the neural networks involved in learning procedural and compare networks recruited among children with specific learning disorder alone or in combination (co-morbidity). The children included in the study have either a Developmental Dyslexia or a Developmental Coordination Disorder, or both. The procedure includes a neuropsychological evaluation and a brain MRI study with a morphological and a functional part. During fMRI the child realizes a automated motor task contrasting with a task involving learning procedural.
Inclusion criteria:
These children presenting either a specific disorder in learning to read (developmental dyslexia or DD) type phonological or mixed as defined by World Health Organisation or a Developmental Coordination Disorder (DCD) as defined by Diagnostic and Statistical Manual IV criteria or the association of both disorders (DCD + DD).
Or in the control group:
Children having no neurological or psychiatric disorder, mental retardation with IQ (Intelligence quotient) > 70 and DCD (score> 15 percentile on the Movement ABC) and Dyslexia (reading delay should not exceed 12 months) The age of children included in the study is between 8 and 12 years. The inclusion of subjects from 8 years is justified to have an optimal level of cooperation of the child in the MRI, in order to determine the status of children for reading and the fact that most of validated neuropsychological tests for reading are for the age 8 to 12 years.
Children and their parents must have given their free and informed consent signed. The representative of the child shall be affiliated to a social security scheme.
The children included in the study will be all right handed.
Exclusion criteria:
Mental retardation as defined by DSM IV criteria by an estimated IQ from the Wechsler scales less than 70.
The presence of a Specific Language Impairment (or dysphasia): a score below -2 SD (standard deviation) in at least one of three tests for language assessment is a criterion for exclusion.
The presence of a dyslexia-type surface defined by a specific disorder in learning to read without difficulty for metaphonological tests and/or an exclusive impairment of the addressing reading route (reading irregular words).
Children regularly practicing a musical instrument conferring a high manual dexterity such as piano or guitar.
Children with neurological or psychiatric disorders as epilepsy for example. Children under psychotropic medication such as anticonvulsant. Treatment with methylphenidate is not an exclusion criterion but treatment should be discontinued at least 48 hours before performing MRI. Children with ADHD according to DSM IV criteria.
The presence of a cons-indication for a MRI.