A closer look at visually guided saccades in autism and Asperger\u27s disorder

Motor impairments have been found to be a significant clinical feature associated with autism and Asperger’s disorder (AD) in addition to core symptoms of communication and social cognition deficits. Motor deficits in high-functioning autism (HFA) and AD may differentiate these disorders, particularly with respect to the role of the cerebellum in motor functioning. Current neuroimaging and behavioural evidence suggests greater disruption of the cerebellum in HFA than AD. Investigations of ocular motor functioning have previously been used in clinical populations to assess the integrity of the cerebellar networks, through examination of saccade accuracy and the integrity of saccade dynamics. Previous investigations of visually guided saccades in HFA and AD have only assessed basic saccade metrics, such as latency, amplitude and gain, as well as peak velocity. We used a simple visually guided saccade paradigm to further characterize the profile of visually guided saccade metrics and dynamics in HFA and AD. It was found that children with HFA, but not AD, were more inaccurate across both small (5°) and large (10°) target amplitudes, and final eye position was hypometric at 10°. These findings suggest greater functional disturbance of the cerebellum in HFA than AD, and suggest fundamental difficulties with visual error monitoring in HFA

Longitudinal Assessment of Antisaccades in Patients with Multiple Sclerosis

We have previously demonstrated that assessment of antisaccades (AS) provides not only measures of motor function in multiple sclerosis (MS), but measures of cognitive control processes in particular, attention and working memory. This study sought to demonstrate the potential for AS measures to sensitively reflect change in functional status in MS. Twenty-four patients with relapsing-remitting MS and 12 age-matched controls were evaluated longitudinally using an AS saccade task. Compared to control subjects, a number of saccade parameters changed significantly over a two year period for MS patients. These included saccade error rates, latencies, and accuracy measures. Further, for MS patients, correlations were retained between OM measures and scores on the PASAT, which is considered the reference task for the cognitive evaluation of MS patients. Notably, EDSS scores for these patients did not change significantly over this period. These results demonstrate that OM measures may reflect disease evolution in MS, in the absence of clinically evident changes as measured using conventional techniques. With replication, these markers could ultimately be developed into a cost-effective, non-invasive, and well tolerated assessment tool to assist in confirming progression early in the disease process, and in measuring and predicting response to therapy

Inhibitory Deficits in Visual Snow

Patients with visual snow (VS) complain of a constant and persistent "static-like" disturbance of the entire visual field, associated with a variety of other phenomena such as palinopsia and tinnitus. The pathophysiology of VS is unknown but cortical hyperexcitability and dysrhythmia have been proposed. We suggest that such dysrhythmia is a consequence of inhibitory dysfunction, leading to the perception of normally convergent, non-visual afferent stimuli. Ocular motor testing has been successfully employed in neurological and psychiatric disorders to demonstrate inhibitory dysfunction. In this study, we used a range of ocular motor tests to investigate inhibitory deficits in patients with VS

Change in AS position error over two years.

<p>Change in AS position error over two years.</p

Correlation between AS errors and PASAT scores in MS patients at two years.

<p>Correlation between AS errors and PASAT scores in MS patients at two years.</p

Mean absolute differences in saccade parameters over two years.

<p>Mean absolute differences in saccade parameters over two years.</p

Change in proportion of AS errors over two years.

<p>Change in proportion of AS errors over two years.</p

Distractibility In Multiple Sclerosis

"Objective: To undertake a pilot study to elucidate objective and reproducible ocular motor abnormalities reflecting cognitive dysfunction in multiple sclerosis (MS). MS patients near universally suffer fatigue and impaired concentration, often prior to clinically evident ""eloquent"" lesions. Pathology in MS is diffuse, affecting widespread interconnecting networks subserving cognition. Dysfunction in these networks represents the commonest manifestations of MS impacting gainful employment, provoking demoralization, and compromising quality of life. An ominous consequence of cognitive impairment involves the predilection for dysphoria, reduced socialization and abulia, compromising adherence to treatment and healthy living.