Journal of experimental zoology. Part A, Ecological and integrative physiologyOct 6, 2018

Nighttime Light Changes Cell Structure in Memory and Thinking Areas, Linked to Brain Problems in Day-Active Crows

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Updated Apr 3, 2026

Abstract

Light at night (LAN) is associated with a significant decrease in soma size of neurons in the hippocampus and lateral caudal nidopallium of Indian house crows.

Exposure to constant light or dim light at night resulted in reduced soma size of neurons, indicating decreased neuronal plasticity.
Neuronal density in both the hippocampus and lateral caudal nidopallium remained unchanged despite the reduced soma size.
A decrease in the number of glial cells was observed, leading to a lower glia-neuron ratio that positively correlated with soma size.
These findings highlight the potential negative effects of LAN on brain cytoarchitecture in a diurnal species.

Simplified

Our previous studies have shown that light at night (LAN) impaired cognitive performance and affected neurogenesis and neurochemistry in the cognition-associated brain regions, particularly the hippocampus (HP) and lateral caudal nidopallium (NCL) of Indian house crows (Corvus splendens). Here, we examined the cytoarchitecture and mapped out the morphology of neurons and glia-neuron density in HP and NCL regions of crows that were first entrained to 12-hr light (LL): 12-hr darkness (LD) and then exposed to the light regime in which 12-hr darkness was either replaced by daytime light (i.e., constant light, LL) or by dim light (i.e., dim light at night, dLAN), with controls continued on LD 12:12. Compared with LD, there was a significant decrease in the soma size, suggesting reduced neuronal plasticity without affecting the neuronal density of both HP and NCL of crows under LL and dLAN conditions. In parallel, we found a reduced number of glia cells and, hence, decreased glia-neuron ratio positively correlated with soma size in both, HP and NCL regions. These results for the first time demonstrate LAN-induced negative effects on the brain cytoarchitecture of a diurnal species and give insight for possible influence on the brain health and functions in animals including humans that might be inadvertently exposed to LAN in an emerging night-illuminated urban environment.

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Nighttime Light Changes Cell Structure in Memory and Thinking Areas, Linked to Brain Problems in Day-Active Crows

Abstract

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