169 Brain Plasticity After Preterm Birth: A Fmri Study of the Visual Pathway

Abstract

Objective: Although a large number of very preterm children follow a normal school cursus, they nevertheless present cognitive difficulties affecting visuo-spatial abilities especially. In this study, we investigated whether these visuo-spatial difficulties could originate in a dysfunction of the visual cerebral pathways (i.e., dorsal and ventral pathways). Methods: A group of 7 young adults (MA = 19.4 ± 0.8 years) who were born preterm (GA: 29.9 ± 1.7 wks), and a group of 7 term born controls (MA = 20.22 ± 1.5 years; GA: 39.14 ± 1.4 wks) underwent a complete neurologic examination, an IQ battery, a standardized motor test and a task which was developed to investigate specific cerebral responses of the dorsal and ventral visual stream, both in terms of processing of visual information (bottom-up) and allocation of attention (top-down). Results: No significant difference between groups was found for IQ, motor performances and behavioral dorsal and ventral functionning. The fMRI data showed an additional activation of ventral occipital areas during dorsal stream tasks in preterms compared to their controls. Conclusion: By showing an additional ventral activation in a task that typically relies on dorsal stream activation, our finding strongly suggest that preterm adults use alternative strategies to behaviorally perform as term born adults. They also suggest that the dorsal stream is more vulnerable during early development and that ventral stream brain areas are more susceptible to plasticity than their dorsal counterparts.