Reviewed by Ben Konynenbelt, OD: Pediatrics and Vision Therapy Resident at Southern College of Optometry
Experience has been demonstrated to influence cognitive development in infants. For instance, both exposure to multiple languages during infancy and breastfeeding have been associated with positive cognitive function. Studies on the birth experience itself, specifically caesarian versus vaginal birth, have correlated an increased risk of diabetes, allergies, and obesity to caesarian section; however, few studies have evaluated the relationship between the birth experience and cognitive development. This study investigated attentional allocation, a function of the somatosensory cortex, in infants 3 months post vaginal or caesarian birth.
Twelve vaginally born and twelve caesarian born infants age 98 to 125 days, born full term (± 2 weeks from due date), and in good health participated in this study. Attention allocation was measured by tracking infants’ saccadic eye movements using an infrared eye-tracking camera. The subjects were presented with a central fixation target followed by an interval with no stimulus and then a peripheral target. A separate group of subjects were presented a fixation cue for the location of the peripheral target during the period containing the central fixation target. This cue served to evaluate the subject’s ability to use bottom-up (stimulus driven) processing to respond to a visual cue. A third group was presented a series of targets alternating in a predictive left-right pattern to assess the infants’ ability to use top-down processing to initiate predictive eye movements. Eye movements of individuals in each treatment group were pooled to increase statistical power.
Whether cued (vaginal, M = 694.27 ms, 95 % CI [621.65, 766.89]; caesarean section, M = 796.88 ms, 95 % CI [708.51, 885.25]) or not (vaginal, M= 775.31ms, 95 % CI [691.19, 859.42]; caesarean section, M = 930.19, 95 % CI [833.64, 1,026.74]), stimulus driven (bottom-up) saccadic eye movements showed greater latency in caesarean born infants relative to those vaginally delivered. Thus, infants born via caesarean section take longer to attend a visual stimulus and initiate eye movement than vaginally delivered infants regardless of visual cueing. This effect is not seen in tasks requiring top-down processing as determined by the infants’ performance on the visual expectation task. There was no significant difference in the latency of saccadic movements toward visual stimuli presented in a predictive manner between caesarean or vaginally born infants (F(1,20) = 0.12, n.s.). This experiment found no significant difference between top-down processing of visual attention in caesarean versus vaginally delivered infants.
Experience before and after birth has been associated with cognitive development. This study confirms that the birth experience itself impacts visual function and specifically the bottom-up (stimulus driven) process of attention allocation that predominates in 3-month old infants. Since top-down processing does not reach a mature state until age 6 months, no difference would be expected between infants born via caesarean or vaginal delivery at 3 months. Further testing must be performed to evaluate the long-term effect of birth experience throughout the stages of cognitive development.