Abstract
Purpose: To determine whether contrast sensitivity in preterm (PT) infants matches that of fullterm (FT) infants when the two groups are of the same postnatal age (PNA), suggesting that sensitivity is governed primarily by visual experience, or the same postconceptional age (PCA), suggesting that sensitivity is governed by “biological maturation”. We compared luminance sensitivity, subserved by the Magnocellular pathway, and chromatic (red/green) sensitivity, subserved by the Parvocellular pathway to investigate how these pathways are influenced by early visual experience.
Methods: Because PT infants born very early can have ocular/neurological abnormalities, we tested “late” PT infants born between 30–35 weeks gestation, a population with ∼1% incidence of abnormal neurological scans. Using forced-choice preferential looking (FPL), contrast sensitivities were obtained for chromatic (red/green isoluminant) and luminance moving sinusoidal gratings (11 × 11°; 0.27 cpd; 4.2 Hz; mean luminance = 20 cd/m2).
Results: At the youngest ages tested (between 2 – 4 months), the luminance sensitivity of PT (n = 59) and FT (n = 132) infants is well matched when the groups are of the same PCA. In contrast, the chromatic sensitivity of PT and FT infants is not well matched when the groups are the same PNA (PT underperform FT) or the same PCA (PT overperform FT).
Conclusions: In the first few months of life, luminance sensitivity, mediated by the M pathway, appears to be governed mainly by biological maturation. By contrast, chromatic sensitivity, mediated by the P pathway, appears to be governed, to some degree, by visual experience.
Funded by NIH (EY-12153).