At First Sight: Fetal Eye Movements Reveal a Preference for Face-Like Configurations From 26 Weeks of Gestation

Area of Science:

• Neuroscience
• Developmental Biology
• Ophthalmology

Background:

• Adults and newborns exhibit preferential responses to face-like configurations (FCs) compared to inverted configurations (ICs).
• Fetal head orientation suggests a prenatal preference for FCs over ICs when visual stimuli are presented through the uterine wall.

Purpose of the Study:

• To determine when during the third trimester fetal preference for FCs emerges.
• To investigate the relationship between this preference and the maturation of specific brain structures.
• To use fetal lens movements as a sensitive measure of FC preference throughout the third trimester.

Main Methods:

• 2D-ultrasound was employed to monitor fetal lens movements in response to FCs and ICs.
• Experiments involved fetuses at 26, 31, and 37 weeks of gestational age.
• Both flashing and continuous light stimuli were used to assess responses.

Main Results:

• Continuous light stimuli elicited significantly more fetal lens movements than flashing stimuli.
• Fetal lens movements showed a linear increase throughout the third trimester.
• A consistent preference for FCs over ICs was observed across all tested gestational ages.
• A positive correlation was found between the differential response to FCs versus ICs and thalamic nuclei size at 26 weeks.

Conclusions:

• Fetal preference for face-like configurations is present from the beginning of the third trimester.
• This early preference is linked to the establishment of thalamocortical projections.
• Fetal eye movements provide a viable method for assessing visual preferences during prenatal development.