Prenatal conditions do not affect brain physiology and learning in a lizard

Abstract

Early environmental factors such as heat or stress hormones can impair learning through brain metabolic function, which is crucial for neural development and synaptic plasticity. However, whether early environments always result in cognitive impairment through changes in neural physiology is not well established outside of a few model systems. Here, we investigated the effects of prenatal temperature and corticosterone (CORT) on brain mitochondrial activity and spatial learning in the delicate skink (Lampropholis delicata). We treated eggs with either CORT or a control vehicle and incubated at cold (23±3°C) or hot (28±3°C) temperatures. Juveniles were tested in a spatial learning task over 40 days after which mitochondrial function in the medial cortex was assessed. Despite among-individual variation in learning ability, mitochondrial physiology and spatial learning in L. delicata remained robust to prenatal temperature and CORT exposure. No significant relationship was found between mitochondrial function and cognitive performance, contrary to predictions. Increased metabolic capacity correlated with higher production of reactive oxygen species but did not affect oxidative damage, possibly as a result of protective mechanisms. These findings highlight the physiological and cognitive resilience of L. delicata to early-life challenges. Future research should explore whether this robustness extends to other brain regions, cognitive domains and life stages.