Interhemispheric cooperation in global–local visual processing in pediatric multiple sclerosis

Abstract

Impairments in visuospatial abilities are commonly reported in children and adolescents with multiple sclerosis (MS). Corpus callosum (CC) pathology occurs in patients with MS and may contribute to impairment in visuospatial perception, particularly when interhemispheric information transfer is required. This study used a global–local hierarchical letter paradigm to examine the relationship between interhemispheric information transfer and white matter integrity in the CC assessed using diffusion tensor imaging. Thirteen cognitively preserved pediatric-onset MS patients and 15 age-matched healthy controls were asked to determine whether a target letter E appeared at the attended level of the stimulus. As expected, both groups processed global and local information more slowly under divided than selective attention conditions. The MS group performed similarly to the control group with respect to reaction time and accuracy on selective and divided attention conditions, with one exception. Specifically, the presence of a global target when attending to a local target caused greater response conflict in the MS group than in controls (p = .01). Pooling both the patient and control data, greater response conflict was associated with reduced white matter integrity as indicated by lower fractional anisotropy in the anterior body of the CC (r = –.33, p < .05). Results suggest that reduced white matter integrity in anterior regions of the CC may lead to less efficient inhibition of task-irrelevant global information in the hierarchal processing of visual information.

Keywords:

• Multiple sclerosis
• Pediatric-onset
• Global–local processing
• Fractional anisotropy
• Visuospatial ability.

Acknowledgements

The authors would like to acknowledge Julie Coleman and Martina Kalahani for their assistance with data collection, Sarah Khan for her assistance with programming and designing the global–local task, and Vicentiu Tipu for his assistance with computing diffusion tensor imaging data. We would also like to thank the patients who generously contributed their time to participate in this study. The research was funded by the Faculty of Health at York University and the MS Society of Canada.

Disclosures: None to report related to the current study.