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Effects of dark rearing and light exposure on memory for a passive avoidance task in day-old chicks
1Brain and Behaviour Research Group, Open University, Milton Keynes, United Kingdom.
Insights
Dark incubation impairs memory in young chicks, affecting retention and discrimination. Prehatch light exposure during specific embryonic days (E19-E20) can reverse these negative effects on chick memory.
Area of Science:
- Developmental neuroscience
- Animal behavior
- Embryology
Background:
- Light exposure is crucial for chick development.
- Dark incubation may negatively impact cognitive functions.
Purpose of the Study:
- To investigate the effects of dark incubation on chick memory.
- To determine if light exposure during embryogenesis can mitigate memory deficits.
Main Methods:
- Domestic chicks were incubated in darkness or with light exposure.
- Passive avoidance tasks and discriminative memory tests were used to assess memory.
- Potential motor, attentional, or visual impairments were ruled out.
Main Results:
- Dark incubation led to impaired retention and reduced discriminative memory in day-old chicks.
- Light exposure during embryonic days 19-20 significantly alleviated these memory deficits.
- The observed effects were not due to motor, attentional, or visual impairments.
Conclusions:
- Prehatch light exposure is vital for normal memory development in chicks.
- Specific timing of light exposure (E19-E20) is critical for mitigating memory impairments caused by dark incubation.
- Further research is needed to understand the underlying neural mechanisms mediating these effects.
Abstract:
Light exposure during embryogenesis is necessary for functional and morphological maturation in the domestic chick. In the present study, dark incubation was demonstrated to induce a weak amnestic effect on retention for a passive avoidance task and a diminution in discriminative memory ability in day-old chicks. Putative explanations based on possible motor, attentional, or visual impairment were excluded. Light exposure of dark-reared eggs, specifically during embryonic days E19 to E20, alleviated the retention and discrimination deficits. The processes which might mediate between prehatch light stimulation and posthatch behavioral effects are discussed.