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

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.

A preliminary transcranial magnetic stimulation study of cortical inhibition and excitability in high‐functioning autism and Asperger disorder

“…20 This is consistent with DSM-IV-TR accounts of motor dysfunction in autism (including stereotyped body movements, which seem to imply a deficit in inhibitory control), and empirical studies of the control of motor activity (including gait variability 6 ) and motor-related brain activity. [10][11][12] By contrast, cortical inhibition appears to be intact in Asperger disorder, suggesting that motor abnormalities (including clumsiness, reduced coordination, and impaired gait) may not be attributable to reduced motor cortical control. Cortical facilitation, largely reflecting glutamatergic processes, 18 appears largely undifferentiated between HFA and Asperger disorder (and generally similar to neurotypical individuals, with the exception of right hemisphere resting motor threshold), despite evidence for cortical glutamatergic dysfunction in autism.…”

“…This is particularly crucial given recent evidence of post-mortem GABA B abnormalities in autism. 10 Larger sample sizes will also allow further exploration of cortical excitability and associations with clinical characteristics (e.g. repetitive behaviours, motor dysfunction), which should be measured in future studies.…”

“…For example, Rinehart et al 10 and Enticott et al 11 report electroencephalographic (EEG) abnormalities over the supplementary motor area (similar to that found in Parkinson disease) in HFA but not in Asperger disorder, indicating a possible frontostriatal dissociation between the two disorders. Further, Muller et al, 12 in their functional magnetic resonance imaging (fMRI) study of autism, found decreased activation of motor-related neural circuitry (e.g.…”

The Rubber Hand Illusion Reveals Proprioceptive and Sensorimotor Differences in Autism Spectrum Disorders

“…At best, weaker versions of the illusion seem to be induced, and RHI on non-hand objects seems to work best with prior induction of the illusion on a hand-like object (Hohwy & Paton, 2010). Given differential processing by the mirror neuron system (MNS) of hand and non-hand objects and their goal directedness (Enticott et al, 2010) it is possible that individuals with ASD, for whom a still widely debated MNS deficit has been posited (Williams et al, 2001;Oberman et al 2005;Iacoboni & Dapretto, 2006;Gallese & Goldman, 1998;Enticott et al, In press), would show a different response than controls to the RHI for non-hand objects. The link from MNS to ASD suggests that observation of hand vs. non-hand objects should differ for ASD and control groups, in particular when the observed hand is, as it in the RHI, viewed in the egocentric rather than allocentric perspective THE RUBBER HAND ILLUSION IN AUTISM SPECTRUM DISORDERS 8 (Théoret et al, 2005).…”

“…For example, differences in body ownership and body image processing could potentially relate to differences in imitation, which require on-line mapping of the body images of self and other . In so far as the RHI affects the body schema, thought to be implicated in motor planning and control, it could THE RUBBER HAND ILLUSION IN AUTISM SPECTRUM DISORDERS 4 also help throw light on observed differences in sensorimotor processes in ASD (Rinehart et al, 2001;Mari et al, 2003;Nazarali et al, 2009;Rinehart et al, 2006).…”