Lubricants play an integral role in the operation of several technologies and in biology also, ranging from moving parts in machinery to the biolubrication of artificial joints. We have found that a colloidal dispersion consisting of easily synthesized highly spherical and uniform graphitic carbon particles results in a very efficient water based "green" and environmentally sustainable lubricant with very low friction coefficients and excellent surface wear protection. These particles use a rolling mechanism similar to nano --or microscale ball bearing under confinement. The effect of particle size on lubrication will be introduced and discussed. Additionally, carbon from sugars and carbohydrates, considered as "green precursors" because of their abundance in nature, have been favored for their low environmental impact and cost when compared to traditional oil based lubricants. The second part of my dissertation presents the fabrication and design of a novel bidirectional membrane device to assist child delivery in resource-limited settings. Approximately one third of pregnancies are delivered by one out of three possible operative methods: vacuum extraction, forceps operation, or caesarean section. Using these traditional devices or alternative methods, the risk of injuring to the mother and the fetus is elevated tremendously in the wake of poor training. Here, I present a polymer-based membrane, which will provide ultra-low friction thus facilitating child delivery but also have the ability to provide high friction when needed for child extraction. Specifically, the friction properties between polydimethylsiloxane (PDMS) and a borosilicate surface were studied using different lubricating media. The dynamics of the anisotropic surface morphology will be discussed and applied to this novel membranous device.

The ability of insulin-like growth factor-I (IGF-I) to impact the hippocampus and associated behaviors may vary depending upon estrogenic status. Previous work from our lab demonstrated that chronic antagonism of brain IGF-I receptors (IGF-IR) resulted in increased levels of hippocampal synaptic proteins in control-treated ovariectomized (OVX) rats. In contrast, antagonism of brain IGF-IR decreased levels of synaptic proteins in estradiol-treated OVX rats. The goal of the current experiment was to test the hypothesis that effects of chronic agonism of IGF-IR, via peripheral treatment with IGF-I, on hippocampal-dependent memory would also vary with estrogenic status. Furthermore, we assessed the influence of estrogenic status on the ability of IGF-I to impact levels of hippocampal synaptic proteins. OVX rats received chronic peripheral treatment with estradiol or cholesterol control via silastic implants, as well as IGF-I or vehicle via osmotic minipumps. One week after surgeries, place learning and memory on the Morris water maze was assessed via eight place-training trials on the first day and four place-training trials on the second day of testing. Place learning and memory was measured using mean swim path length. Following place training, a probe trial was conducted to assess memory for the location of the hidden platform. Memory on the probe trial was measured via percent time in the target quadrant. Animals were euthanized 24 hours following behavioral testing, and hippocampi were processed for western blotting to determine levels of hippocampal synaptic proteins PSD-95, spinophilin, and synaptophysin. Results revealed no effects of treatment on behavioral measures or on levels of hippocampal synaptic proteins. These data indicate that chronic peripheral administration of IGF-I does not affect hippocampal-dependent memory in a Morris water maze task and does not impact hippocampal synaptic protein levels in the presence or absence of peripheral estradiol. / acase@tulane.edu

ABSTRACT The ability to regulate attention is a key function of several cognitive activities, especially mindfulness and working memory capacity (WMC). In each moment, we are bombarded with both relevant and irrelevant sensory information in our immediate environment, and attentional control is needed to minimize distractions and maximize productivity. Attentional control plays an important role in the practice and embodiment of mindfulness, but it also functions with WMC in similar ways. Both mindfulness and WMC require the individual to regulate his or her attention in such a way that new information can be incorporated and old information, if relevant, can be maintained. In order to further understand the underlying attentional control mechanisms pertaining to mindfulness and WMC, we utilized a component of electroencephalographic response data known as the mismatch negativity (MMN), which provides information about automatic attention orienting. Participants completed a mindfulness survey, spatial (SSPAN) and verbal (OSPAN) WMC tests, and were recorded on EEG while watching a silent movie and listening to tones that changed in frequency. We expected mindful individuals and individuals with high WMC to exhibit larger MMN amplitudes than less mindful and low WMC individuals. We also expected a positive correlation between mindfulness and WMC due to their similar functionalities. Our results showed that mindful individuals actually exhibit smaller MMN amplitudes, and there was no correlation between mindfulness and WMC. Our results also showed a positive correlation between SSPAN and the response to the frequency change. / acase@tulane.edu

acase@tulane.edu

Extensive research in both humans and animals has identified and isolated distinct brain regions essential for different types of memory, supporting the notion of multiple memory systems (MMS). The hippocampus and the striatum are the two systems that have been studied widely and are the focus of our studies. Research involving lesion and pharmacologic manipulations on both memory systems show strong evidence for independence. However, recent evidence suggests that both memory systems can interact as well. Though evidence point also in favor interactions, the mechanisms under which these systems interact are unknown. The experiments in this dissertation primarily focused on understanding how these two systems operate in a normally functioning brain. Two methods were used to investigate our notions: 1) Behavioral experiment measured cellular changes in the levels of phosphorylated CREB (pCREB) in the regions of interest (ROI) 2) Somatic experiments measured changes in the behavior following manipulation of CREB selectively in the ROI. Overall, these experiments demonstrate CREB as a critical neuronal marker that can be used in both interventions. Behavioral intervention experiment showed evidence as a plasticity related changes in the levels of pCREB that suggested both the hippocampus and the striatum might act in a competitive manner, bidirectionally. The somatic intervention experiments used lentiviral (LV) vectors and showed evidence that LV CREB manipulations are suitable for chronic stable expression and can be used to investigate multiple tasks following a single manipulation. LV mutant CREB in the hippocampus impaired memory across two different hippocampus-dependent tasks and demonstrated that CREB is critical for long term memory. Overexpression of wild type CREB in the striatum enhanced striatal memory, but also showed evidence for hippocampus competition and cooperation. Similarly, CREB overexpressed in the hippocampus of young and middle-aged rats demonstrate that CREB might be a rate limiting factor in young, but not in the middle-aged rats. / acase@tulane.edu

Evidence from previous studies on the multiple memory systems model suggests that specific brain regions cooperate and compete to mediate the navigational strategies used to locate a goal in a spatial environment. Specifically, the cholinergic system within these discrete brain regions plays a key role in balancing this mediation such that acetylcholine release, genomic changes, and receptor regulation at cholinergic synapses are altered following learning and subsequent memory consolidation. Based on previous findings, we proposed to test learning-induced changes in muscarinic receptor binding expression in adult male rats following training on a water maze task guided either by a cue proximal to the escape platform (stimulus-response strategy), by cues surrounding the maze (place strategy) or by alternating between the two strategies (strategy-switching). The primary findings of the current study demonstrate that adult male rats that navigated to an escape platform guided by cues surrounding a water maze (place-trained) learned the task at a significantly slower rate than males that were guided by a cue proximal to the platform (stimulus-response-trained) or males that were required to switch strategies on alternating days. Additionally, males that were required to switch strategies over alternating days expressed higher ratios of muscarinic binding in the hippocampus relative to the striatum compared to place-trained rats, stimulus-response-trained rats, and swim-only controls. These results indicate that the use of a place learning strategy slows acquisition of a water maze task while the requirement to switch strategies as the demands of the task change over days engages the cholinergic system in the hippocampus most heavily. Taken together, the results from the current study further confirm the involvement of cholinergic function in regulating the balance between multiple memory systems. / acase@tulane.edu

Metaphors are employed in order to improve communication and foster our understanding of other persons. Labeling outgroup members as something other than human, however, is dehumanizing and suggests that the targets lack human qualities. Past research operates under the assumption that all forms of animalistic dehumanization inform a single perception of a group of people. The present research, following a “metaphor-enriched†perspective of social cognition, instead suggests that there are two common animalistic metaphoric frameworks for women that inform distinct impressions of women: the aggressive predator and the submissive prey. Male and female participants primed with a “woman-as-predator,†“woman-as-prey,†or “woman-as-person†metaphoric framework revealed their impressions of and intentions toward several nondescript women engaging in ambiguous behaviors. Responses to open-ended questions revealed that, consistent with predictions, perceivers interpret women’s ambiguous behavior as more predator-like (aggressive, rude, or blunt) after exposure to a predator metaphor, and more prey-like (e.g., friendly, mild, forgetful) after exposure to a prey metaphor. Animalizing metaphors were also expected to inform behavioral intentions (predators require taming, while prey require paternalistic care), but results did not support predictions. Instead, gender alone influenced behavioral intentions (with women reporting greater intentions to assist) suggesting that social-role expectations may exert more influence on behavioral intentions than metaphoric framings do. / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

The goal of the current experiments was to assess the role of estrogen receptor alpha (ERë±) in the ability of a prior, short-term exposure to estradiol in mid-life to enhance cognition and affect the hippocampus in aging, ovariectomized rats, as well as to investigate a possible mechanism involving the insulin-like growth factor-1 system by which ERë± may exert these effects. In Experiment 1, rats were trained on the radial maze, ovariectomized, and implanted with estradiol or cholesterol vehicle capsules for 40 days. Rats then continuously received JB1 or aCSF vehicle i.c.v. and were tested on delay trials on the radial maze. Using Western blotting, I determined effects of treatment on protein levels of ERë±, ChAT, IGF-1R, IGF-1BP2, and phosphorylated and total p42/p44 MAPK and Akt in the hippocampus. Antagonism of IGF-1 receptors blocked the ability of prior estradiol exposure to enhance cognition and increase ERë±, phosphorylated ERK/MAPK, and ChAT in the hippocampus. The second experiment was divided into two parts. In Experiment 2A, rats were trained on the radial maze and ovariectomized. After 40 days, rats underwent stereotaxic surgery to receive lentiviral delivery of the gene encoding for ERë± or control virus to the hippocampus, and were then tested on delay trials. Using Western blotting, I determined if proteins of interest previously found to be affected by a prior exposure to estradiol in Experiment 1 would be affected by treatments for all subsequent experiments. Lentiviral delivery of ERë± to the hippocampus was sufficient to enhance cognition and increase phosphorylation of ERK/MAPK in the hippocampus. In Experiment 2B, rats were trained on the radial maze, ovariectomized, and implanted with estradiol or cholesterol vehicle capsules for 40 days. Rats then continuously received an ER antagonist or aCSF vehicle i.c.v. and were tested on delay trials. Antagonism of ERë± blocked the ability of prior estradiol exposure to enhance cognition. In the third experiment, rats were trained on the radial maze, ovariectomized, and implanted with estradiol or cholesterol vehicle capsules for 40 days. Rats then underwent stereotaxic surgery to receive i.c.v. cannula. Infusion of an ERK/MAPK inhibitor or aCSF vehicle was administered every 12 hours during delay trials. Inhibition of ERK/MAPK did not block the ability of prior estradiol exposure to enhance cognition, although it did block an increase in levels of ERë± in the hippocampus. Altogether, these results indicate that ERë± plays an important role in the ability of prior estradiol exposure to enhance cognition and affect the hippocampus in aging, ovariectomized rats, and likely interacts with the IGF-1 system and its associated ERK/MAPK signaling pathway. / acase@tulane.edu