title: Delayed early primary visual pathway development in premature infants: high density electrophysiological evidence.
abstract: In the past decades, multiple studies have been interested in developmental patterns of the visual system in healthy infants. During the first year of life, differential maturational changes have been observed between the Magnocellular (P) and the Parvocellular (P) visual pathways. However, few studies investigated P and M system development in infants born prematurely. The aim of the present study was to characterize P and M system maturational differences between healthy preterm and fullterm infants through a critical period of visual maturation: the first year of life. Using a cross-sectional design, high-density electroencephalogram (EEG) was recorded in 31 healthy preterms and 41 fullterm infants of 3, 6, or 12 months (corrected age for premature babies). Three visual stimulations varying in contrast and spatial frequency were presented to stimulate preferentially the M pathway, the P pathway, or both systems simultaneously during EEG recordings. Results from early visual evoked potentials in response to the stimulation that activates simultaneously both systems revealed longer N1 latencies and smaller P1 amplitudes in preterm infants compared to fullterms. Moreover, preterms showed longer N1 and P1 latencies in response to stimuli assessing the M pathway at 3 months. No differences between preterms and fullterms were found when using the preferential P system stimulation. In order to identify the cerebral generator of each visual response, distributed source analyses were computed in 12-month-old infants using LORETA. Source analysis demonstrated an activation of the parietal dorsal region in fullterm infants, in response to the preferential M pathway, which was not seen in the preterms. Overall, these findings suggest that the Magnocellular pathway development is affected in premature infants. Although our VEP results suggest that premature children overcome, at least partially, the visual developmental delay with time, source analyses reveal abnormal brain activation of the Magnocellular pathway at 12 months of age.
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada; Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Tremblay
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada.
authors.forename: Phetsamone
authors.initials: P
authors.lastname: Vannasing
authors.affiliation: Département d'Ophtalmologie, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada.
authors.forename: Marie-Sylvie
authors.initials: MS
authors.lastname: Roy
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada.
authors.forename: Francine
authors.initials: F
authors.lastname: Lefebvre
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Damelan
authors.initials: D
authors.lastname: Kombate
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada; Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Maryse
authors.initials: M
authors.lastname: Lassonde
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada; Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: McKerral
authors.affiliation: Centre de Recherche, Centre Hospitalier Universitaire Ste-Justine, Montréal, Québec, Canada; Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Gallagher
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology; D003430:Cross-Sectional Studies; D065839:Edinger-Westphal Nucleus / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D020670:Islands of Calleja / Q000502:physiology / Q000503:physiopathology*; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology / Q000503:physiopathology*