Memory Deficits and Inflammatory Cytokines in the Hippocampus in a Rat Model of ADHD
Student name: Lucy Anderson
Project advisor: Dr. Marta Sabariego
Attention deficit hyperactivity disorder (ADHD) is a heterogeneous behavioral disorder characterized by hyperactivity, impulsivity, and inattention, as well as deficits in both working memory (WM) and sense of time1 . Although animal models cannot fully reflect human psychiatric disorders, they can provide insight into the disorder that cannot be obtained from human studies2 . The spontaneously hypertensive rat (SHR) is one of the best-studied animal models of ADHD. In comparison to their control, the Wistar-Kyoto (WKY) rat, male SHRs show multiple behavioral phenotypes characteristic of ADHD, including hyperactivity, impulsivity, and poor sustained attention3 . In addition, there is increasing evidence that SHRs show impairments in learning and memory4 . The hippocampus has long been known to be a key brain region for learning and memory, and hippocampal lesions or inactivations in rats cause poorer performance in multiple memory tasks, including elapsed time discrimination and spatial WM tasks5 . Inflammatory signaling is also known to be connected to memory and cognitive deficits6 ; however, the precise role that cytokines play in the modulation of ADHD behavioral symptoms remains unknown. To investigate this question, I have examined the behavior of SHRs and WKY rats in multiple hippocampal-dependent memory tasks. We used rats of both sexes in an effort to rectify the current sex imbalance in knowledge about ADHD and to directly examine sex as a biological variable. I then analyzed the levels of several inflammatory cytokines (IL-1a, IL-1b, IL-4, IL-6, IL-10, IL-18, and TNFa) in the dorsal and ventral hippocampus of female and male SHRs and WKY rats in order to better understand the impact of inflammatory signaling on spatial and temporal memory in SHR and WKY rats. The results of my behavioral assays will be discussed in relation to the levels of cytokines in the hippocampus of SHRs and WKY rats and the impact of inflammation on memory and cognition in ADHD.

What Are the True Sizes of Retired A Stars?
Student name: Lauren Leese
Project advisor: Darby Dyar
To find exoplanets, it is important to have accurate measurements for potential host stars to make it easier to tell when something changes that might indicate the presence of an exoplanet. A-type stars, which have up to about twice the mass of our Sun, rotate very fast, making it hard to see if an exoplanet's gravity is tugging on them. However, when these stars have aged and cooled into subgiants, they rotate slower, making it easier to spot planets around them. This project uses near-infrared data from Georgia State University’s Center for High Angular Resolution Astronomy (CHARA) on Mount Wilson, CA, to accurately measure the radii of five retired A stars. Models make it possible to predict the stars’ luminosity, temperature, age, and mass from the radii measurements. The measurements of these five properties are then compared to the properties estimated by existing literature, which generally uses broad-band photometric data and derives the radius using a chart rather than measuring it directly. Hypothetically, there will be a systematic offset in the measured values as compared to the literature values. This comparison will help to refine the models and lead to more accurate measurements of retired A star radii -- and lead to more exoplanet discoveries.

Urosalpinx cinerea: Drilling into local adaptation
Student name: Emma Rawson
Project advisor: Justin Baumann
As anthropogenic climate change continues to affect environmental characteristics of marine ecosystems, the capacity of marine life to acclimatize or adapt to those changes becomes increasingly relevant. This work focuses on the adaptive and/or acclimatory capacity of the marine gastropod Urosalpinx cinerea (Atlantic oyster drill) to ocean warming using a common garden experiment. Common garden experimental designs are useful for identifying trait differences and possible tradeoffs at the population level; the traits exhibited are likely to be temperature-dependent and/or inherited from their parents. U. cinerea is an ectotherm and is expected to have a higher performance at higher temperatures until a thermal optimum is exceeded (Villeneuve et al. 2021). Using growth as a proxy for thermal performance, Villeneuve et al. (2021) found that populations of U. cinerea were locally adapted, but the extent of the tradeoffs and the mechanism behind them are not well understood. Cornwell et al. (2020) found a positive correlation between boldness and growth, and no strong correlation between resting metabolic rate and growth, suggesting that behavioral traits have an important role in the fitness of the periwinkles studied.
To assess (I) the effect of chronic summer temperature exposure on physiological performance and behavioral response, (II) whether there is a difference in physiological performance and behavioral response between population groups, I reared the offspring of latitudinally-separated populations of U. cinerea (parents coming from sites in New Hampshire and North Carolina) in a reciprocal common garden experiment. Urosalpinx cinerea juveniles of parents from NH and NC were placed in one of two temperature treatments (22oC and 27oC, mean summer sea surface temperatures at NH and NC, respectively) for 8 weeks. I measured shell height, righting response, boldness response, movement speed, displacement from origin, and a distance metric as response variables and found significant effects of population on all metrics, and an expected effect of temperature on shell height. There was significant evidence that NC as a group was faster and bolder than the group of NH, and that some of these differences were exacerbated by temperature exposure. The difference in behavioral and physiological traits suggests that the oyster drill populations are locally adapted, though the mechanism behind this remains unclear.

Reward Loss Drives Drug-seeking Behavior During Dorsal Hippocampal Inactivity
Student Name: Eleftheria Vogiatzoglou
Project Advisor: Marta Sabariego
Reward loss triggers an aversive emotional state called frustration that derives from the comparison between the present and the memory of past rewards (Amsel, 1992). The adaptive value of frustration resides in its ability to cause a rapid change in learning and performance, preventing perseverance on no-longer rewarded responses (Torres & Papini, 2017). Thus, frustrative nonreward facilitates a switch from responses that do not yield rewards to a search mode that may result in the discovery of needed resources. Previously, we have demonstrated that animals without a functional hippocampus show behavioral impairments to adjust to frustrative nonreward. However, it is unclear whether the impairment is due to a lack of emotionality (i.e. hippocampal lesioned/inactivated rats not feeling frustrated after reward loss) or a lack of cognitive flexibility (i.e. hippocampal lesioned/inactivated rats unable to modify previously learned goal-directed responses). Because negative states powerfully increase drug value even after extinction, we reasoned that if hippocampal-inactivated rats did not feel frustration then drug-seeking behavior would not change after reward downshifts. In order to investigate this question, we exposed rats (with active and inactive dorsal hippocampi) to a reward-loss paradigm alongside a conditioned place preference (CPP) task. In particular, animals were first infused with inhibitory designer receptors exclusively activated by designer drugs (DREADDs). After recovering from surgery, rats were conditioned to acquire a drug associated place preference. Subsequently, they were trained to recognize two reward sites on a figure-8-maze: one site containing 12 sugar pellets (large reward) and the other containing two sugar pellets (smaller reward). Each day––following this training phase in the figure-8-maze––animals were exposed to cocaine CPP extinction sessions. Once animals extinguished their preference for the cocaine-paired side, all rats were injected with clozapine-N-oxide and the large reward in the figure-8-maze task was devalued to equal the smaller reward. Following this devaluation, rats were immediately exposed to the CPP apparatus. We found that while hippocampus-inactivated rats did not adjust their behavior in the figure-8-maze task after the reward downshift, they increased their time spent in the side previously paired with cocaine similarly to control rats. These results suggest that animals with a dysfunctional dorsal hippocampus do not lack emotionality but rather experience cognitive inflexibility. Our data could contribute to revealing the function of the dorsal hippocampus in goal-directed behavior and adaptation to loss.

How do childrens' neural responses to rhythm predict reading skill?
Student name: Yutong(Kelly) Li
Project advisor: Mara Breen
Using event-related potentials (ERPs), we can non-invasively record real-time neural activity in both adults and children, giving insight into the time-course of complex cognitive processes. We can use this method to assess a range of questions about attention, memory, perception, and language processing. In the current study, we are using ERPs to explore the relationship between metric processing and reading comprehension.
Spoken prosody predicts silent reading comprehension but the causal relationship between these skills is not clear (Breen, et al., 2016). Our hypothesis is that children’s sensitivity to meter - the organization of stresses over time - is an important predictor of this relationship.
To investigate metric processing skill in children, we are adapting a study of imagined meter originally conducted with adults. In the original study (Fitzroy & Sanders, 2020), adults listened to strings of isochronous, pitch-invariant tones, and were asked to perceive the tones in groups of 3 or 4, corresponding to either a 3-beat or 4-beat metrical organization. The behavioral results indicated that adults are able to group the beats into an intended meter. When looking at the ERP results from adults, the first (strong) beat in each 3-beat or 4-beat group results in a larger negativity from 80-120 ms compared to the other (weaker) beats showing that adults allocate more attention to metrically strong beats than metrically weak beats.
In the current study, we will use the same test of imagined metric organization but instead of adults, we will test children ages 6-10. They will complete the ERP study of meter processing as well as a standardized reading comprehension assessment taken from the Kaufman test of educational achievement (KTEA; Kaufman & Kaufman, 2014). We predict that, like adults, children’s ERP results will demonstrate greater attention to strong beats than weak beats. Moreover, we predict that children who are better at reading comprehension will show greater effects of metric organization as demonstrated by larger early negativities than children who demonstrate poorer reading comprehension.