Developmental Medicine & Child Neurology



Original Articles

Movement-related potentials in high-functioning autism and Asperger's disorder


Nicole J Rinehart  a1 c1, Bruce J Tonge  a1, John L Bradshaw  a2, Robert Iansek  a3, Peter G Enticott  a1 and Katherine A Johnson  a2
a1 Centre for Developmental Psychiatry and Psychology, Australia.
a2 Experimental Neuropsychology Research Unit, School of Psychology, Psychiatry and Psychological Medicine, Monash University, Victoria, Australia.
a3 Geriatric Research Unit, Kingston Centre, Southern Health, Australia.

Abstract

Autism and Asperger's disorder (AD) are neurodevelopmental conditions that affect cognitive and social-communicative function. Using a movement-related potential (MRP) paradigm, we investigated the clinical and neurobiological issue of ‘disorder separateness’ versus ‘disorder variance’ in autism and AD. This paradigm has been used to assess basal ganglia/supplementary motor functioning in Parkinson's disease. Three groups (high functioning autism [HFA]: 16 males, 1 female; mean age 12y 5mo [SD 4y 4mo]; AD: 11 males, 2 females; mean age 13y 5mo [SD 3y 8mo]; comparison group: 13 males, 8 females; mean age 13y 10mo [SD 3y 11mo]) completed a cued motor task during electroencephalogram recording of MRPs. The HFA group showed reduced peak amplitude at Cz, indicating less activity over the supplementary motor area during movement preparation. Although an overall significant between-group effect was found for early slope and peak amplitude, sub-analysis revealed that the group with AD did not differ significantly from either group. However, it is suggested that autism and AD may be dissociated on the basis of brain–behaviour correlations of IQ with specific neurobiological measures. The overlap between MRP traces for autism and Parkinson's disease suggests that the neurobiological wiring of motor functioning in autism may bypass the supplementary motor area/primary motor cortex pathway.

(Published Online March 16 2006)
(Accepted June 24 2005)


Correspondence:
c1 Department of Psychological Medicine, Monash Medical Centre, 246 Clayton Rd, Clayton, Victoria 3168, Australia. E-mail: nicole.rinehart@med.monash.edu.au