Orientation and motion-specific visual cortex responses in infants born preterm.

Orientation-specific cortical responses develop earlier in infancy than motion-specific responses. The maturation of orientation-reversal and direction-reversal visual evoked potentials was evaluated in 17 healthy, low risk, preterm infants (born <32 weeks gestation), compared with a group of 26 infants born at term. Both groups were studied at a corrected age of 2-4 months. The age function and magnitude of the orientation-reversal responses was similar in the two groups. Direction-reversal responses across the age range, however, were smaller in the preterm infants, suggesting a delayed maturation of motion processing. Reasons for the vulnerability of motion processing are discussed; the results may reflect anomalies of white matter development in preterm infants that are undetected by ultrasonography.