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Neural noise limitations on infant visual sensitivity
1Smith-Kettlewell Eye Research Institute, San Francisco, California 94115, USA. sko@skivs.ski.org
Insights
Newborns have significantly higher neural noise, limiting visual contrast sensitivity. This noise decreases as infants develop, improving vision and demonstrating early development of visual inhibition mechanisms.
Area of Science:
- Developmental Neuroscience
- Visual Perception
- Infant Vision
Background:
- Infant visual contrast sensitivity improves from birth to 8 months.
- Early vision limitations are attributed to physical factors like eye size and photoreceptor density.
Purpose of the Study:
- To investigate the role of neural noise in infant visual sensitivity.
- To determine the developmental trajectory of neural noise and its impact on contrast sensitivity.
- To examine the presence and function of contrast gain control in neonates.
Main Methods:
- Employed non-invasive electrophysiological measurements.
- Utilized a visual noise titration technique to quantify intrinsic neural noise.
Main Results:
- Neonatal intrinsic neural noise is approximately nine times higher than in adults.
- Infant contrast sensitivity improves proportionally as intrinsic neural noise decreases.
- Contrast gain control operates in infants as young as 6 weeks, despite high neural noise.
Conclusions:
- Intrinsic neural noise critically limits visual contrast sensitivity during infant development.
- Early-developing contrast gain control in neonates may form a basis for later visual inhibition.
Abstract:
Visual contrast sensitivity is poor in newborn human infants, but improves rapidly to approach adult levels by 8 months of age. During this period, infant sensitivity can be limited by physical factors affecting photon capture, such as eye size and photoreceptor density. Here we show that infant visual sensitivity is also limited by high levels of noise in the neural transduction process. Using a non-invasive electrophysiological measurement and a visual noise titration technique, we have found that intrinsic neural noise in neonates is approximately nine times higher than in adults. As intrinsic neural noise decreases during infancy, contrast sensitivity improves proportionally, suggesting that neural noise places critical limits on contrast sensitivity throughout development. Moreover, contrast gain control, an inhibitory process that adjusts visual responses to changing stimulation, is in place and operating in infants as young as 6 weeks of age, in spite of high levels of neural noise and significant immaturities in contrast sensitivity. The contrast gain control that we observed in human neonates may serve as a building block for more complex forms of visual inhibition, which develop later in infancy.