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As urbanization spreads, understanding its impact on wildlife is increasingly urgent. By comparing the traits and fitness of individuals within the same species found in both urban and rural habitats (urban adapters), we can better understand the behavioral and physiological coping mechanisms wild birds employ in the face of rapid environmental change. For my dissertation, I investigated the physiological, behavioral, and fitness differences between urban and rural living song sparrows (Melospiza melodia) to explore how song sparrows are adjusting to urban environments. In my first chapter, I investigated urban birds' termination of the glucocorticoid stress response by looking at their ability to reduce circulating levels of glucocorticoid 'stress' hormones and the relative abundance of receptors that provide negative feedback in the hippocampus and hypothalamus. I found that urban males have a lower relative abundance of glucocorticoid receptors and the enzyme 11β-HSD2 in the hippocampus compered too rural, though we found no difference in negative feedback at the periphery, as both urban and rural song sparrows responded similarly to a challenge with synthetic glucocorticoid (dexamethasone). In chapter 2, I asked if increased aggression, which has been rigorously documented in urban males, is also expressed by females, and whether this aggressive signaling is constraining other reproductive behaviors such as maternal care. Indeed, female song sparrows, like males, expressed increased aggressive signaling compared to rural, suggesting urban habitats may favor a more aggressive phenotype. Finally, in Chapter 3, I investigated the consequences of increased male aggression on their social partners and offspring by measuring parental care and nestling outcomes across urban and rural habits. I was unable to establish a trade-off between parental care and aggression in either sex, suggesting this increased aggression is not constraining other reproductive behaviors. In fact, the more aggressive urban males visited the nest significantly more frequently, a trend also seen in urban females during the daylight hours, though the relationship was not significant over a 24-hour period. Additionally, urban birds had significantly higher reproductive metrics compared to rural, though they also had the added cost of increase brood parasitism by brown-headed cowbirds (Molothrus ater) compared to rural. Overall increased urban aggression was associated with higher reproductive success without any reduction in paternal care. Additionally, we found physiological differences in the glucocorticoid stress response system associated with the differences in habitat but whether theses differences represent mechanisms of acclimation or potential costs of living in urban habitats is not yet clear. / Doctor of Philosophy / As urbanization spreads, understanding its impacts on wild bird conservation is increasingly urgent. By comparing the behaviors and reproductive success of animals living in urban and rural habitats (urban adapters), we can better understand the coping mechanisms wild birds' employ in the face of this form of rapid environmental change. In my dissertation, I compared the physiology, behavior, and reproductive success of urban and rural song sparrows (Melospiza melodia) to explore the changes song sparrows make to survive and reproduce in urban environments. In my first chapter, I investigated how urban birds terminate their stress response by looking at their ability to reduce circulating levels of stress hormones and the relative abundance of "shut down" targets in the brain. In chapter 2, I asked if increased aggression, regularly document in urban males, is also expressed by females, and whether this aggression is constraining other reproductive behaviors. Finally, in Chapter 3, I investigated the consequences of increased male aggression on their social partners and offspring by measuring parental care and nestling outcomes across urban and rural habits. I found that urban males have a lower relative abundance of one type of "shut down" target, and a lower abundance of a potentially protective enzyme in the hippocampus, though we found no difference in how quickly urban and rural birds cleared stress hormone from their blood. Female song sparrows, like males, expressed increased aggressive signaling compared to rural, suggesting urban habitats may favor a more aggressive pattern of behavior. However, I was unable to establish a trade-off between parental care and aggression in either sex, suggesting increased aggression is not constraining other reproductive behaviors. In fact, the more aggressive urban males visited the nest significantly more often, a trend also seen in urban females during the daylight hours, though the relationship was not significant over a 24-hour period. Additionally, urban birds had significantly higher reproductive metrics compared to rural, though they also had the added energetic cost of increased brood parasitism by brown-headed cowbirds (Molothrus ater), compared to rural. Collectively, my results suggest that individuals of this species, the song sparrow, may benefit from livening in low intensity urban habitats and that living in such altered environments favors or permits higher aggression.

The purpose of this study was to examine language organization in the brain by using a series of three tasks concurrent with event-related potentials (ERPs) to investigate both hemispheric differences and interhemispheric reactions. Overall, the findings from this study support a relative rather than absolute hemispheric specialization for language processing. Despite an overall RVF (LH) advantage, both hemispheres were capable of performing the tasks and benefited from semantic priming.

Conclusion: The results suggest that ASD children have deficits in attentional and inhibitory control. Frontal dysfunction and weak ACC engagement in ASD were supported as the underlying neuronal inefficiency. / Methods: 20 children with high-functioning ASD [Mean Age (SD): 10.75 years old (2.07 years); Mean IQ (SD): 101.4 (16.8)] and age- and IQ-matched normal children (NC) [Mean Age (SD): 9.80 years old (1.88 years); Mean IQ (SD): 110.7(17.8)] were investigated electrophysiologically during performance of a visual Go/NoGo task. An electrophysiological source localization method was employed to further analyze the data. Several different neurospsychological tests were also performed to provide behavioral measures on attention and inhibition. / Objectives: To investigate neurophysiologic abnormalities in frontal and anterior cingulate cortex underlying attentional and inhibitory control in children with Autism Spectrum Disorder (ASD). / Results: ASD children showed a significantly task-related lower frontal theta activity. This effect was associated with a significantly reduced activation of the anterior cingulate cortex (ACC). Both groups also differ significantly regarding the behavioral aspects of attention and inhibition. / Leung, Shuk Yin Connie. / "November 2009." / Adviser: Chan Sue-Yin Agnes. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 65-85). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Thesis (Ph.D.)--University of Chicago, 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--University of Michigan, 2001. / Includes bibliographical references.

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As we strive to understand the mechanisms underlying neural computation, mathematical models are increasingly being used as a counterpart to biological experimentation. Alongside building such models, there is a need for mathematical techniques to be developed to examine the often complex behaviour that can arise from even the simplest models. There are now a plethora of mathematical models to describe activity at the single neuron level, ranging from one-dimensional, phenomenological ones, to complex biophysical models with large numbers of state variables. Network models present even more of a challenge, as rich patterns of behaviour can arise due to the coupling alone. We first analyse a planar integrate-and-fire model in a piecewise-linear regime. We advocate using piecewise-linear models as caricatures of nonlinear models, owing to the fact that explicit solutions can be found in the former. Through the use of explicit solutions that are available to us, we categorise the model in terms of its bifurcation structure, noting that the non-smooth dynamics involving the reset mechanism give rise to mathematically interesting behaviour. We highlight the pitfalls in using techniques for smooth dynamical systems in the study of non-smooth models, and show how these can be overcome using non-smooth analysis. Following this, we shift our focus onto the use of phase reduction techniques in the analysis of neural oscillators. We begin by presenting concrete examples showcasing where these techniques fail to capture dynamics of the full system for both deterministic and stochastic forcing. To overcome these failures, we derive new coordinate systems which include some notion of distance from the underlying limit cycle. With these coordinates, we are able to capture the effect of phase space structures away from the limit cycle, and we go on to show how they can be used to explain complex behaviour in typical oscillatory neuron models.

Surface chemical modifications are presented for supporting primary neurons in culture. The initial substrates for culture were glass and gold. The surface modifications were based on self assembled monolayer (SAM) approaches. Glass surfaces were initially modified by silanisation with either 3-aminopropyltrimethoxysilane (APTMS) or 3-aminopropyldimethylethoxysilane (APDES), to present amino-terminated surfaces. Gold surfaces were initially modified by thiol SAMs of either 11-amino-1-undecanethiol (AUT) or a peptide fragment of laminin (PA22-2), to present an amino- or peptide-terminated surface respectively. The amine-terminated surfaces of both glass and gold were subject to further modification. A heterobifunctional linker, containing a polyethylene glycol (PEG) spacer, was used to couple the peptide PA22-2 to the amino-terminated surfaces. Surface modifications were characterised using WCA, XPS and ToF-SIMS. The heterobifunctional linker bound homogeneously across the AUT SAM surface, however the linker was not distributed evenly on either of the amino silanisations of glass. Primary neurons from dissociated embryonic rat hippocampi were cultured on the modified glass and gold surfaces. The cell viability was measured during a 3 week long culture using calcein and ethidium homodimer fluorescence. Neuronal cell cultures were viable on all the gold surface modifications. The only viable glass surface was a control surface of adsorbed poly-l-lysine (PLL) on glass. Cell viability on the AUT and the Peptide-PEG-AUT modified gold surfaces was equivalent to the PLL coated glass. Inclusion of the PEG linker reduced protein adsorption from the media to the peptide modified gold surface, allowing cells to recognise the peptide rather than an adsorbed protein layer and improving their viability. The presented gold surface modifications provide suitable substrates for neural cultures which can be used in existing applications for investigating neural activity, such as; multi-electrode arrays, micro-fluidics devices, and surface plasmon resonance.

Aberrant neurotransmitter function promotes cognitive deficits in schizophrenia. These abnormalities in functioning are seen as disruptions in attentional and information processing, as well as disruptions in the consolidation and retrieval of information. Tasks of attentional salience and memory that are used to model these disruptions include the latent inhibition (LI) task of attentional salience, prepulse inhibition (PPI) task of sensorimotor gating and an Episodic memory (EM) task, which is an index of memory for episodes at a particular point in time. Aberrant functioning of candidate genes that are associated with risk for schizophrenia may be seen as behavioural alterations in these tasks of schizophrenia relevant phenotypes. dopaminergic hyperactivity and hypofunction have been implicated in mediating disruptions on these cognitive tasks. Increased transmission in the dopamine system in the striatal region promotes schizophrenia symptoms, and indirect dopamine (DA) agonist Amphetamine worsens these symptoms in patients, and disrupts schizophrenia relevant behaviours on these cognitive tasks. We investigated the effects of deletion of two genes relevant to schizophrenia on cognitive tasks known to be disrupted in the disorder. The effect of deletion of the dopamine D2 receptor (D2R) and trans membrane (TM) domain Neuregulin-1 (Nrg-1) receptor were investigated in mediating disruptions in cognitive processes in an animal model of schizophrenia. The role of the D2R in an attentional model of sensorimotor gating was assessed. PPI was attenuated in D2R knock out (KO), in a one day sensorimotor gating task. In a one day PPI test protocol, amphetamine disruptions on PPI were spared in D2R WT and KO mice. Following on from previous reports of disrupted LI by a single low dose amphetamine injection, separated by 24h interval, we established a single vs. two low dose PPI protocol in order to facilitate a direct comparison of amphetamine induced disruption in LI with PPI. A one injection (prior to test only) vs. two injection (prior to habituation and prior to test) task was established. In the two day protocol, a single low dose of amphetamine disrupted PPI in D2R KO mice and reduced startle reactivity to the 120 dB pulse alone trials. Two low dose injections of amphetamine however, do not disrupt PPI in D2R KO or their WT littermates, and do not mimic low dose amphetamine disruptions in the LI task. These findings demonstrate that prior conclusions about the requirement of the D2R for amphetamine effects in PPI does not generalise to all dose regimens. Episodic memory was also investigated as a measure of cognitive impairment in schizophrenia. D2R KO mice show sex specific dissociations on an EM task. Male D2R WT and KO animals show equal exploration of old vs. recent objects on the what-when component of the EM task, and female KO animals show enhanced memory for old vs. recent objects. Both D2R WT and KO mice show intact memory for displaced objects. These deficits were also investigated in the TM domain Nrg-1 model. Nrg-1 has been implicated as a candidate gene for schizophrenia, and behavioural phenotypes assessing its role in cognitive impairment in schizophrenia were established. Intact LI is seen in both Nrg-1 WT and Het animals. Nrg-1 TM domain Het mutants also show deficits on the schizophrenia relevant PPI task. Nrg-1 Het mutants show attenuated % PPI compared to their WT littermates, which reflects interrupted sensorimotor gating in schizophrenia. Lastly, we found some evidence that reduced function of TM-domain of the Nrg-1 gene disrupted episodic-like memory (what- where-when recognition) in males and improved it in females.