Neuronal communication in Autism Spectrum Disorders: synchrony and coherence in the motor system

Autism Spectrum Disorders (ASD) are a group of developmental disorders
classically defined in terms of a triad of impairments in social interaction,
communication and behavioural flexibility (DSM IV). Besides these core
impairments, abnormalities are also seen in several other behavioural and
neuropsychological domains like the sensory and motor domain. Research from
different fields (e.g. genetics, neurochemistry and neuroimaging) suggests that
ASD are based on a pathophysiological substrate that affects brainfunction
globally. One theory that has received a lot of attention is the
*disconnectivity theory*. This theory states that functional brain areas are
underconnected in autism, while connections within functional areas would be
atypically strong causing dysfunctional neuronal communication and
collaboration. Because synchronization of oscillatory neuronal activity is
thought to be a mediator of effective neuronal communication the theory is
formulated that atypical synchronization plays part in ASD being a
disconnectivity disorder. However, more research is needed to test this
hypothesis, focusing on both short-range and long-range synchronization between
neuronal groups.

The overall objective of this study is to increase our understanding of the
neural basis of ASD. The first main objective is to test the hypothesis that
ASD, compared to a contrast group (ADHD) and a healthy control group, is based
on dysfunctional neuronal connectivity, in which local and long-range neuronal
synchrony is disturbed. The second main objective is to test the hypothesis
that motor impairments in autism are correlated to dysfunctional
synchronization and that, while motor impairments decrease with age,
dysfunctions in synchronization too decrease with age.

To test our hypotheses the motor system will serve as a modelsystem to measure
on. Synchronization patterns over motorcortex and coherence between neuronal
activity in motorcortex and spinal alpha-neurons will be characterized during a
simple motortask using magnetoencephalography (MEG) and electromyography
(EMG).

MEG/EMG recording sessions will take no longer than 45 minutes divided into
three blocks with brakes in between. Answering questionaires will take
approximately half an hour. The proposed study includes brain imaging
procedures that have already been applied to a very large scale in normal
subjects and in subjects with various conditions (including ASD), and without
side-effects or unwanted effects. The staffs of the FC Donders Centre and the
Department of Psychiatry (including Karakter Child and Adolescent Psychiatry)
have considerable expertise in the application of these brain imaging
procedures, and scientific research with patients with ASD. The proposed study
does not include invasive measures. The anticipated scientific merits justify
the proposed study, in spite of the fact that no therapeutic or other direct
benefit to the participants is to be expected.