Ed Freedman and John Foxe have just published preliminary data from a study examining eye movement changes in individuals with Autism Spectrum Disorders (ASD), particularly looking at the role of the cerebellum (DOI: 10.1111/ejn.13625). The cerebellum, Latin for ‘little’ brain, sits at the base of brain, underneath the cerebral cortex. Although it has been called ‘mini’, the cerebellum actually has more neurons, or cells, than the cerebral cortex. Classically considered to play a role in the control of movements and the learning of motor patterns, it is now known to play a role in emotion and cognition through its connection to the rest of the brain. And, there is evidence that the structure of the cerebellum is altered in a sub-population of individuals with ASD.
In the current paper, Ed and John present the results of experiments tracking the rapid eye-movements made when looking from one object to another, or saccades, in individuals with ASD. Accuracy and precision are maintained by careful comparison of the movement command produced by the brain and the results of the actual movement. Any differences between these lead to adjustments of the commands for ensuing saccades. This type of sensorimotor adaptation is dependent on the proper functioning of the cerebellum. However, there is anatomical evidence that some people with an ASD have cerebella with slightly altered structure. If the cerebellar structure is altered, is its function also altered in this sub-group of people? Assessing the ability of people with an ASD to adapt saccade amplitudes is one way to determine whether this function of the cerebellum is altered in ASD.
Another point of interest is determining if the deficits in saccades relate to any of the other key symptoms observed in ASD.
If saccade adaptation deficits do turn out to be a consistent finding in a sub-group of children with ASD, this raises the possibility that saccade adaptation measures may have utility as an early-detection endophenotype. Changes in cerebellar structure most likely occur in utero and very recent work has shown that saccadic adaptation can be measured in children as young as 10-41 months of age is a most encouraging development indeed. - Ed and John