Global Motion Perception in 4.5-year-old Children Born at Risk of Abnormal Neurodevelopment

Abstract

AIM Dorsal extrastriate visual areas, which include regions specialized for motion processing, are thought to be particularly vulnerable to the effects of abnormal neurodevelopment. This thesis aimed to test the hypothesis that global motion perception, an index of dorsal stream function, would be affected by two distinct perinatal risk factors for abnormal neurodevelopment: prenatal exposure to recreational drugs and neonatal hypoglycemia. Both of these risk factors are commonly reported among infants in developed countries. METHODS Global motion perception was assessed using random dot kinematograms in a large cohort of 4.5-year-old children who participated in one of two multi-disciplinary, longitudinal studies; the Infant Development, Environment and Lifestyle (IDEAL) study or the Children with Hypoglycemia and their Later Development (CHYLD) study. This thesis is divided into four parts. The first part explored the influence of early visual functions, such as contrast sensitivity for motion direction discrimination and visual acuity on global motion perception in 4.5-year-old children. The second part focused on the association between global motion perception and neuromotor functions, both of which are thought to involve the dorsal stream. The third and fourth parts investigated whether global motion perception was affected by prenatal exposure to recreational drugs or neonatal hypoglycemia respectively. RESULTS Global motion perception was found to be independent from contrast sensitivity and visual acuity. Moreover, global motion perception was associated with neuromotor function in children born at risk of abnormal neurodevelopment. With regard to neurodevelopmental risk factors, global motion perception was significantly affected by prenatal drug exposure whereby exposure to alcohol worsened and exposure to marijuana improved motion processing in children. In addition, global motion perception was significantly poorer in children who experienced neonatal hypoglycemia compared to children who were euglycemic despite having risk factors for neonatal hypoglycemia. CONCLUSIONS Global motion perception in children reflects visual function beyond the stage of contrast encoding and is associated with motor function. Global motion perception is also influenced by perinatal risk factors in children. These results are consistent with the dorsal stream vulnerability hypothesis and support the use of global motion perception as a tool to investigate abnormal neurodevelopment in children.