Visuo-spatial learning and memory deficits in C57BL/6 mice following postnatal ethanol exposure.

Background

Postnatal alcohol exposure impairs the development of the central nervous system, including the visual system. The behavioral consequences of such exposure on visual function remain poorly understood.

Objectives

In this study, we investigated the effects of postnatal ethanol exposure on visuospatial learning and memory in C57BL/6 mice.

Methods

Ethanol (3.0 g/kg) was administered via intubation on postnatal days 3-20. Controls received intubation only or no intervention. Pups were assigned to alcohol-treated (A, n = 11), intubation control (IC, n = 11), or non-intubated control (C, n = 9) groups. At three months, mice underwent the Novel Object Recognition (NOR) test and a visual water task. The NOR test measured recognition memory and exploratory behavior. The visual water task assessed visual acuity using sinusoidal gratings presented on monitors. Mice were trained over 17 days to associate a grating with a hidden platform, and visual acuity thresholds were determined based on performance at varying spatial frequencies.

Results

Alcohol-exposed mice showed significant deficits in recognition memory and visual acuity. No group differences in body weight were observed. However, alcohol-treated mice displayed reduced exploration of novel objects (p = .0085, R2 = 0.29) and lower visual acuity thresholds at higher spatial frequencies (p = .048, R2 = 0.24).

Conclusion

These findings demonstrate that early postnatal alcohol exposure can lead to lasting impairments in visual-cognitive functions. Given their similarity to deficits seen in children with Fetal Alcohol Spectrum Disorders (FASD), our results suggest the importance of early behavioral and visual assessments in children with suspected prenatal or early postnatal alcohol exposure.