In order to effectively study the interactions that occur between neurons found in the brain, spatially and after an extended period of time, it is necessary to have reliable, repeatable studies. This is difficult to accomplish through conventional two-dimensional cell culture techniques, but three dimensional (3D) elastomer foams satisfy these criteria. Here we present a platform to study complex neuronal networks for extended periods in vitro. Elastomer foams were constructed with pore sizes ranging from 150μm to 400μm with 40μm secondary pores which allowed human neuroblastoma cells (SH-SY5Y) to adhere and interact with the foam and be sustained for long term studies, over 60 days. Through confocal imaging, it is shown that neuroblastoma cells mature while extending neurites and extensions while grown on the elastomer. Being able to sustain neurons for this length of time in 3D arrangements allows for a better representation of the interactions that occur in 3D tissues, making this method applicable for studying neurodegenerative disease states.

We analyzed the behavior of two separate impala (Aepyceros melampus) herds within the Wits Rural facility in Limpopo Province, South Africa. We hypothesized that fawns would spend less time vigilant than the adults and would spend more time in social interactions and foraging. We also hypothesized that the alpha (dominant) male would spend a greater portion of his time vigilant than the adult females, who would spend a greater amount of time foraging. The two herds were separated by roughly 2 km in a lightly forested savanna biome. There were 20-40 individuals in each herd. Each herd consisted entirely of mothers and fawns with a single alpha male among the herd. Random individuals within the herds were selected and their behaviors were recorded from a distance every 15 seconds. Observations on individuals varied in duration from 5-30 minutes. Date, time of day and habitat were also recorded during each observance. Eleven standard behaviors were observed. These behaviors included: foraging, vigilance, nursing, fawn-tending, excretion, interactions with other individuals (notes of the interactions were made), other (notes of their behavior were made), individual became out of view, vocalizations, grooming, and bedding down.

Stress has been shown to induce adverse effects such as depression, heart disease, and hypertension (Roman et al., 2016, Aschbacher et al., 2016, Ojike et al., 2016). Following a stressful event there is an increase in circulating glucocorticoids, primarily cortisol in humans and corticosterone (CORT) in rodents. CORT is primarily controlled via the PVN, the major regulating structure in the hypothalamic-pituitary-adrenal axis (HPA axis, Ferguson et al., 2009). Normally, stressful stimuli causes activation of the PVN, triggering the release of CRH from the hypothalamus, subsequently causing the release of ACTH from the anterior pituitary gland, resulting in the production of CORT from the adrenal cortex that will negatively feedback to regulate its release.

When the HPA axis is dysregulated, CORT can become over secreted and result in depression-like behaviors (Goshen et al., 2008). However, the majority of research today uses superphysiological levels of CORT (10-15mg/kg CORT) to induce the depressive-like behavior in rats (Johnson et al., 2010). As a result, there are still discrepancies of whether the administration of superphysiological levels of CORT follows the same mechanism of stress exposure to induce depressive-like behaviors. To resolve this issue, we propose the superphysiological levels of CORT are only necessary when the circadian timing of the CORT administration is not adequately controlled.

This current work is a mechanistic study to determine whether we are able to activate the PVN and ultimately increase rat CORT levels though designer receptor exclusively activated by designer drugs (DREADD) technology. DREADDs have been used to control cellular activity in both a spatial and temporal manner to successfully analyze neural circuitry previously, and is used in this experiment to induce transcription of cellular receptors to mediate the cell response, allowing control over circulating CORT levels (American College of Neuropsychopharmacology, 2012). It is hypothesized that once the CNO ligand has been injected and binds with the DREADDs, the PVN will be activated and result in an increase of CORT.

Our original intention was to carry out a giving-up density experiment with three troops of Vervet monkeys Cercopithecus aethiops at the Wits Rural Research Facility in eastern South Africa. We placed 7 lidded buckets containing peanuts and wood blocks at different heights within, and distances away from, three marula treesSclerocyra birrea where separate troops foraged. The presence of the wood blocks mimicked the time and effort spent while naturally foraging, and the hole in the lid (6 cm) was smaller than the sizes of the wooden pieces (7 cm diameter). The amount of peanuts eaten from each bucket after a foraging period indicates that these were the more favorable feeding patches - where they felt the safest (lowest predation risk), and spent the most time foraging. We realized that the amount of natural, more easily accessible food sources to the monkeys was large because it was summer in South Africa. They had no interest in our buckets of peanuts while there was ample fresh food nearby. As a result, we switched tactics to observation-based data collection. We found the most visible troop and spent multiple days taking ethogram observations of as many individuals as possible. Every 15 seconds, the behavior of every individual in the sample was recorded. Behaviors such as vigilance, foraging, and interacting with peers and offspring were common. These ethogram samples suggest the comfort level of the troop in their environment, their apparent stress towards food source availability, and their perception of nearby predation risk.