Greater Disruption to Control of Voluntary Saccades in Autistic Disorder than Asperger’s Disorder: Evidence for Greater Cerebellar Involvement in Autism?

Abstract

It remains unclear whether autism and Asperger's disorder (AD) exist on a symptom continuum or are separate disorders with discrete neurobiological underpinnings. In addition to impairments in communication and social cognition, motor deficits constitute a significant clinical feature in both disorders. It has been suggested that motor deficits and in particular the integrity of cerebellar modulation of movement may differentiate these disorders. We used a simple volitional saccade task to comprehensively profile the integrity of voluntary ocular motor behaviour in individuals with high functioning autism (HFA) or AD, and included measures sensitive to cerebellar dysfunction. We tested three groups of age-matched young males with normal intelligence (full scale, verbal, and performance IQ estimates >70) aged between 11 and 19 years; nine with AD, eight with HFA, and ten normally developing males as the comparison group. Overall, the metrics and dynamics of the voluntary saccades produced in this task were preserved in the AD group. In contrast, the HFA group demonstrated relatively preserved mean measures of ocular motricity with cerebellar-like deficits demonstrated in increased variability on measures of response time, final eye position, and movement dynamics. These deficits were considered to be consistent with reduced cerebellar online adaptation of movement. The results support the notion that the integrity of cerebellar modulation of movement may be different in AD and HFA, suggesting potentially differential neurobiological substrates may underpin these complex disorders.

The Effect of Performing a Dual Task on Postural Control in Children with Autism

“…Indeed, the results show that the surface area of the CoP is smaller during the fixation task, and it increased during pursuits reaching larger values during saccades. This finding could be due to the poor oculomotor performances reported in these kinds of children [34, 35], but it could also be due to the fact that autistic children have difficulty in shifting attention [36]. Consequently, performing a dual-task is very difficult for them.…”

A closer look at visually guided saccades in autism and Asperger’s disorder

“…AD is currently differentiated from autism by the absence of clinically significant delays in language (single words used by age 2 years, communicative phrases used by age 3 years), and no delays in cognitive development (American Psychiatric Association, 2000). In addition to the core symptoms associated with autism and AD, motor impairments have been consistently reported in these groups (Fournier et al, 2010) impacting postural control (Gepner and Mestre, 2002), fine motor (Cartmill et al, 2009), upper limb (Martineau et al, 2004; Papadopoulos et al, 2012; Rinehart et al, 2006b,c), and ocular motor control (Takarae et al, 2004; Nowinski et al, 2005; Stanley-Cary et al, 2011). Green et al (2002) also found that motor performance on the Movement Assessment Battery for Children, which assesses manual dexterity, aiming and catching, and balance, was significantly correlated with IQ across children with autism and AD (Green et al, 2009).…”

“…Although the primary site of pathology within the cerebellum is unclear in AD, there is a general consensus the degree of cerebellar disruption is more limited in AD than in autism (Lotspeich et al, 2004; Bauman and Kemper, 2005; Catani et al, 2008; Yu et al, 2011). The cerebellum, in particular vermis lobules VI–VII and the fastigial nuclei, are crucial to the control of eye movements (Ohtsuka and Nodu, 1995; Barash et al, 1999), and several investigations of functional impairment associated with cerebellar abnormalities have used ocular motor paradigms in autism and AD (Takarae et al, 2004; Nowinski et al, 2005; Stanley-Cary et al, 2011). …”

Ischaemic stroke: the ocular motor system as a sensitive marker for motor and cognitive recovery

“…Processes which disrupt brain tissue may be reflected in the assessment of cognitive processing required for ocular motor function. To this end, ocular motor studies, particularly those including paradigms to evaluate the cognitive processing of sensory input that influences motor output, have demonstrated significant characteristic abnormalities in degenerative diseases (Parkinson's disease,10–14 Huntington's disease14–16), developmental disorders (autism spectrum disorders17) and lesional diseases, such as multiple sclerosis 18–21…”

“…[4][5][6][7][8][9] Processes which disrupt brain tissue may be reflected in the assessment of cognitive processing required for ocular motor function. To this end, ocular motor studies, particularly those including paradigms to evaluate the cognitive processing of sensory input that influences motor output, have demonstrated significant characteristic abnormalities in degenerative diseases (Parkinson's disease, [10][11][12][13][14] Huntington's disease [14][15][16] ), developmental disorders (autism spectrum disorders 17 ) and lesional diseases, such as multiple sclerosis. [18][19][20][21] Cognitive processes, such as attention ( prioritisation of sensory input), inhibitory control (the capacity to delay responses and ignore distraction), working memory, and learning and decision making processes, influence saccadic parameters.…”