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Maternal stress is a common adversity during pregnancy. Gestational corticosterone alternations are thought to contribute to the etiology of postpartum behavioral disturbances. However, the impact of stress during pregnancy, in particular noise exposure, on gestational corticosterone fluctuations and spatial cognition in postpartum mice has not been fully understood yet. We hypothesized that noise exposure during pregnancy negatively affects gestational corticosterone levels and postpartum memory function in the dams similar to the physical stressors. Pregnant C57BL/6 mice were randomly assigned to either one of two stress conditions or a control condition. The noise stress (NS) was induced by presenting a loud intermittent 3000 Hz frequency on gestational days (GDs) 12, 14, and 16 for 24 hours, whereas the physical stress (PS) consisted of restraint and exposure to an elevated platform on GDs 12-16. Plasma corticosterone level was collected on GDs 11 and 17, and Morris water task (MWT) was carried out 30 days after parturition. Compared to the control group, the level of corticosterone in the stressed groups was significantly increased on GD17 relative to GD11. Significantly longer swim time and lower swim speed were observed in both stressed groups relative to the control group. Probe time was significantly shorter in the NS group than the other groups. The delta corticosterone level was significantly correlated with the swim time as well as the probe time in the three groups. Given the results, the adverse effects of gestational noise exposure on the hypothalamic pituitary-adrenal (HPA) axis activation and postpartum spatial learning and memory function were as large as/ or a bit stronger than the physical stresses. The findings suggest the significance of conservation against loud noise exposure in daily living, as well as need to further notice to the different aspects of gestational stress in mothers' behavior like offspring.

In the current research on measuring complex behaviours/phenotyping in rodents, most of the experimental design requires animal-experimenter interaction in which the animal is removed from its home-cage environment and placed in an unfamiliar apparatus (novel environment). This may influence behaviour, general well-being, and metabolism of the animal, effecting the phenotypic outcome even if the data collection method is automated. Most of the commercially available solutions for home-cage monitoring are expensive and usually lack the flexibility to be incorporated with the existing home-cages. Here we present a low-cost solution for monitoring home-cage behaviour of rodents that can be easily incorporated practically with any available rodent home-cage. This system is based on a Raspberry Pi (RPi), which is a low-cost (35$) credit-card sized single board computer. We developed a web interface that allows the user to view the animal activity in the home-cage in real-time and to change camera settings, start/stop recording, download saved videos/images and control peripherals attached to the general-purpose input/output (GPIO) pins of the Raspberry Pi. In addition, we provide custom written scripts for offline tracking, activity monitoring and synchronously acquire video from multiple cameras. To demonstrate the use of our system, we collected sleep-wake behavioural data of animals (n=5) for 200 min and simultaneously recording hippocampal local field potential (LFP) and electromyography (EMG) data. From the video data, the periods of continuous inactivity that were longer than 40 secs were identified as sleep periods. It was observed that these inactive periods are 91.6% ± 0.4 accurate with respect to LFP/EMG recordings, suggesting a prominent application of our system in sleep and circadian rhythm studies. In conclusion, this paper presents an innovative and flexible methodology for studying rodent behaviour with minimal experimenter interference. Our approach for automated acquisition of video-based behavioural data provides a tool that facilitates the analysis of behavior as a medium to study brain function.