Development of lateral interactions in the infant visual system.
The development of lateral inhibitory interactions in the infant visual system, as reflected by the visual-evoked potential (VEP), was studied using a radial, asymmetrical windmill-dartboard stimulus. This contrast-reversing stimulus generates VEP responses with a strong fundamental frequency component and an attenuated second harmonic component (relative to that obtained using a symmetrical stimulus). These two harmonic components reflect distinct phenomena, and appear to be the result of short-range (the fundamental) and long-range (attenuated second harmonic) lateral inhibitory interactions elicited by differential luminance-modulation of contiguous spatial regions. We studied the development of the short- and long-range interactions at 100% and 30% contrast in human infants using both VEP amplitude and phase measures. Attenuation of the second harmonic (long-range interactions) was adult-like by 8 weeks of age while the strength of the fundamental (short-range interactions) was adult-like by 20 weeks suggesting a differential development of long-range and short-range interactions. In contrast, corresponding phase data indicated significant immaturities at 20 weeks of age for both the short- and long-range components.
Sokol
S
S
New England Eye Center, Tufts University School of Medicine, Boston, MA 02111.
Zemon
V
V
Moskowitz
A
A
D015350:Contrast Sensitivity; D005074:Evoked Potentials, Visual; D006801:Humans; D007223:Infant; D014785:Vision, Ocular / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology