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Updated: Sep 30, 2026
Windowing Chicken Eggs for Developmental Studies
Published on: October 1, 2007
Light-incubation effects on lateralisation of single unit responses in the visual Wulst of domestic chicks
Giacomo Costalunga1,2, Dmitry Kobylkov1, Orsola Rosa-Salva1
1Center for Mind/Brain Science, University of Trento, Piazza Manifattura 1, 38068, Rovereto, TN, Italy.
Insights
Embryonic light exposure influences brain development in chicks, affecting visual lateralisation and neural response properties in the visual Wulst. This study reveals both light-dependent and independent asymmetries, impacting visual unit maturation.
Area of Science:
- Neuroscience
- Developmental Biology
- Comparative Psychology
Background:
- Domestic chicks are a key model for studying environmental and genetic influences on brain development.
- In-egg light exposure induces neuroanatomical asymmetries in chick visual pathways.
- The physiological impact of these asymmetries on the visual Wulst remains largely unknown.
Purpose of the Study:
- To investigate the visual response properties of neurons in the left and right visual Wulst of chicks.
- To determine the effect of embryonic light incubation on bilaterally responsive cells.
- To provide direct evidence of lateralisation in visual Wulst neural response properties.
Main Methods:
- Electrophysiological recordings from visually responsive units in the visual Wulst of dark- and light-incubated chicks.
- Analysis of neural response properties, focusing on bilaterally responsive cells.
- Comparison of hemispheric differences in neural function.
Main Results:
- First direct evidence of lateralisation in the neural response properties of visual Wulst units.
- Confirmation that embryonic light exposure induces some forms of visual lateralisation.
- Identification of light-independent asymmetries and a significant effect of light on general functional properties in both hemispheres.
Conclusions:
- Embryonic light exposure influences visual lateralisation and neural response properties in the chick visual Wulst.
- The impact of light extends beyond lateralisation, affecting the maturation of visual units in both hemispheres.
- Findings highlight the complex interplay between environmental stimuli and brain development.
Abstract:
Since the ground-breaking discovery that in-egg light exposure triggers the emergence of visual lateralisation, domestic chicks became a crucial model for research on the interaction of environmental and genetic influences for brain development. In domestic chick embryos, light exposure induces neuroanatomical asymmetries in the strength of visual projections from the thalamus to the visual Wulst. Consequently, the right visual Wulst receives more bilateral information from the two eyes than the left one. How this impacts visual Wulst's physiology is still unknown. This paper investigates the visual response properties of neurons in the left and right Wulst of dark- and light-incubated chicks, studying the effect of light incubation on bilaterally responsive cells that integrate information from both eyes. We recorded from a large number of visually responsive units, providing the first direct evidence of lateralisation in the neural response properties of units of the visual Wulst. While we confirm that some forms of lateralisation are induced by embryonic light exposure, we found also many cases of light-independent asymmetries. Moreover, we found a strong effect of in-egg light exposure on the general development of the functional properties of units in the two hemispheres. This indicates that the effect of embryonic stimulation goes beyond its contribution to the emergence of some forms of lateralisation, with influences on the maturation of visual units in both hemispheres.
