Visual and visuo-cognitive development in children born very prematurely: ‘dorsal vulnerability’ extended

Abstract

Because visual cortical functions develop rapidly in the months after term, they provide a sensitive indicator of disruption to normal brain development (Atkinson, The Developing Visual Brain, OUP 2000). We have used two indicators of early cortical development, the orientation reversal VEP, and attention shifts under competition, to test at-risk infants born very prematurely (<32 weeks gestation). In healthy neurologically normal preterm infants these measures show a similar developmental course to that of term infants. Deficits and delays in these functions correlate with the severity of white matter damage seen on term MRI in infants in the at-risk group.

Follow up of these preterm infants to age 6 (n=78), with a range of measures of visual and perceptual function, visuomotor development, spatial cognition, attention and executive function, show that even those who showed little or no white matter damage on MRI nonetheless perform on average below norms of spatial, perceptual and attentional function, including motion coherence sensitivity, although language development and form coherence sensitivity are normal. The relation of these measures to early visual cortical indicators will be discussed.

Principal components analysis on all these measures for preterm 6–7 year olds shows one component related to frontal function and another to broadly parietal function, with temporal lobe functions largely unaffected. The components revealed, and the relation between form and motion coherence sensitivity, extend the phenomenon of ‘dorsal stream vulnerability’ seen in a wide range of developmental disorders such as Williams syndrome, autism, and fragile X.

Website: http://www.psychol.ucl.ac.uk/vdu/publications.html

Footnotes

 Medical Research Centre grant G7908507