Neuroscience and Neurobiology Commons^™

Characterization Of The Circadian Properties Of Runt-Related Transcription Factor 2 (Runx2) And Its Role In The Suprachiasmatic Nucleus, Meghan E. Reale

Electronic Thesis and Dissertation Repository

Circadian rhythms orchestrate physiological, behavioral and cognitive processes in order to anticipate and adapt organisms to key environmental cues. These endogenously driven oscillations are generated by a network of interlocked auto-regulatory transcriptional-translational feedback loops driven forward by the Bmal1/Clock heterodimer transcription factor. Given the ubiquitous and dynamic quality of circadian rhythms, the identification of factors involved in the coordination and regulation of the endogenous oscillations is central in broadening our understanding of biological timing systems. In an examination of gene expression in the mammalian central circadian pacemaker, the hypothalamic suprachiasmatic nucleus (SCN), revealed a previously unreported rhythmic expression of runt-related …

Septohippocampal Gabaergic Neurons Mediate The Altered Behaviors Induced By N-Methyl-D-Aspartate Receptor Antagonists., Jingyi Ma, Siew Kian Tai, L Stan Leung

Physiology and Pharmacology Publications

We hypothesize that selective lesion of the septohippocampal GABAergic neurons suppresses the altered behaviors induced by an N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine or MK-801. In addition, we hypothesize that septohippocampal GABAergic neurons generate an atropine-resistant theta rhythm that coexists with an atropine-sensitive theta rhythm in the hippocampus. Infusion of orexin-saporin (ore-SAP) into the medial septal area decreased parvalbumin-immunoreactive (GABAergic) neurons by ~80%, without significantly affecting choline-acetyltransferase-immunoreactive (cholinergic) neurons. The theta rhythm during walking, or the immobility-associated theta induced by pilocarpine, was not different between ore-SAP and sham-lesion rats. Walking theta was, however, more disrupted by atropine sulfate in ore-SAP than …

An Investigation Of The Neural Mechanism By Which The Prefrontal Cortex Facilitates Anti-Saccade Task Performance, Michael J. Koval

Electronic Thesis and Dissertation Repository

Cognitive control enables us to guide our behaviour in an appropriate manner, such as rapid eye movements (saccades) toward a location or object of interest. A well-established test of cognitive control is the anti-saccade task, which instructs subjects to look away from a suddenly-appearing stimulus. The dorsolateral prefrontal cortex (dlPFC) and anterior cingulate cortex (ACC) are part of a cortical saccade control network that influences the superior colliculus (SC), which sends saccade commands to the brainstem saccade generator. To compare and contrast the roles of the dlPFC and ACC in saccade control, the cryoloop method of reversible cryogenic deactivation was …

An Investigation Into The Combined Effects Of Β-Amyloid Toxicity And Cerebral Ischemia On The Pathological Expression Of Gangliosides., Jeffrey D. Hepburn

Electronic Thesis and Dissertation Repository

Identifying mechanisms underlying the synergistic pathological interaction between stroke and Alzheimer’s disease (AD) can effectively guide future therapeutic strategies for these highly co-morbid conditions. Aberrant ganglioside expression marked by the pathological accumulation of ganglioside GM3 is common to stroke and AD, yet it is unclear whether GM3 is synergistically enhanced in a comorbid model, or if GM3 is a viable therapeutic target. Adult male Wistar rats received a unilateral ischemic striatal infarct via endothelin-1 (ET-1) injection alone or in combination with bilateral intracerebroventricular injection of the β-Amyloid 25-35 peptide (Aβ) to induce generalized Aβ toxicity (Aβ/ET-1). Animals were sacrificed after …

Sexual Reward And Depression, Andrea R. Di Sebastiano

Electronic Thesis and Dissertation Repository

Sexual behavior in male rats is a complex rewarding behavior and many neurotransmitters and neuropeptides play an important role in mediation of sexual performance, motivation and reward. The hypothalamic neuropeptide orexin has been shown play a key role in reward associated with food and drugs of abuse, but the role of this neuropeptide in control of sexual performance, motivation and reward is currently unclear. First, it was shown that orexin neurons in the hypothalamus are activated during sexual performance and reward. Next, using cell specific lesions of orexin neurons it was demonstrated that orexin is involved in arousal and anxiety, …

Neuroprotective Effects Of Long-Term Endurance Training On The Cortical Autonomic Network In The Aging Brain, Torri A. Luchyshyn

Electronic Thesis and Dissertation Repository

This study tested whether long-term endurance training in older adults (ET; n = 15, 55 ± 4 years, relative VO₂max = 50 ± 8 ml/kg/min) would alter cardiovagal control and preserve the cortical autonomic network compared to age-matched controls (CON; n = 15, 56 ± 4 years, relative VO₂max = 37 ± 9 ml/kg/min). The hypothesis predicts 1) altered deactivation patterns of the ventral medial prefrontal cortex (vMPFC) in response to isometric hand grip (IHG) and 2) greater indices of cardiovagal control; a) increased baroreflex sensitivity at rest, b) greater heart rate change (ΔHR) and c) …

Familiality Of Auditory Evoked Potentials: Preliminary Investigation Of The Auditory Brainstem Response And Late Latency Cortical Response, Matthew B. Lucas

Electronic Thesis and Dissertation Repository

Twenty-four participants, consisting of six sibling pairs and six non-sibling pairs, participated in this study investigating the familiality of auditory evoked potentials (AEPs). The auditory brainstem response (ABR) recorded at high stimulus rates, revealed that Wave V latency increases, while amplitude decreases as stimulus rate increases. ABR Wave V latency was also found to increase with click position within a stimulus train, plateauing by the third stimulus. No evidence for familiality was found with respect to the ABR Wave V under these conditions. The late latency response (LLR) components N1 and P2 were found to decrease between the first and …

Fmri Reveals The Neural Correlates Of Real And Pantomimed Tool Use In Humans, Joseph Umberto Paciocco

Electronic Thesis and Dissertation Repository

Although functional magnetic resonance imaging (fMRI) can be used to study the neural mechanisms underlying greatly expanded cognitive functions in humans like tool use, surprisingly little fMRI research has been done on actual tool use. In fact, due to technical constraints, most fMRI studies have used pantomimed actions as a proxy for real use. However, human neuropsychology patients who are impaired at pantomiming often improve when handling a tool suggesting potential neural differences. We used fMRI to record brain activation while 13 right-handed participants performed one of two tasks, real or pantomime tool use with one of two tools, a …

Investigating Binding Partners Of The Neuronal Adaptor Protein Shcc Involved In Learning And Memory, Kayla Rm Driver

Electronic Thesis and Dissertation Repository

Learning and memory are complex processes: many signaling pathways must come together to start the process of long-term potentiation (LTP), an improvement in the connection between two neurons as a result of a previous signal. LTP involves both the TrkB and NMDA receptor signaling cascades, and there is evidence to support cross-talk between TrkB and the NMDA receptor subunit NR2B using adaptor proteins. ShcC is thought to be involved in learning and memory as ShcC knockout mice have increased hippocampal LTP and better performance in Spatial Memory tasks (Miyamoto et al., 2005). Our results indicate that ShcC binds to both …

On Sensorimotor Function And The Relationship Between Proprioception And Motor Learning, Jeremy D. Wong

Electronic Thesis and Dissertation Repository

Research continues to explore the mechanisms that mediate successful motor control. Behaviourally-relevant modulation of muscle commands is dependent on sensory signals. Proprioception -- the sense of body position -- is one signal likely to be crucial for motor learning. The present thesis explores the relationship between human proprioception and motor learning.

First we investigated changes to sensory function during the adaptation of arm movements to novel forces. Subjects adapted movements in the presence of directional loads over the course of learning. Psychophysical estimates of perceived hand position showed that motor learning resulted in sensed hand position becoming \emph{biased} in the …

The Characterization Of The Fibroblast Growth Factor Receptor Substrate 3 And Its Role In Regulating Microtubule Dynamics And Molecular Transport In The Brain, Sarah J. Gamble

Electronic Thesis and Dissertation Repository

The neuronal cytoskeleton is responsible for governing dynamics such as neurite extension and cortex development. In particular, microtubules (MTs) and their associated proteins, and molecular motors, have been shown to be critical in many neuronal processes such as intracellular molecular transport and neuron differentiation. The fibroblast growth factors (FGFs) act as powerful morphogens that have been shown to play a role in regulating cortical development. FGFs activate receptor tyrosine kinases, of which fibroblast growth factor receptor substrate 3(FRS3) has been shown to interact with, to mediate downstream signaling cascades (regulating cell proliferation and differentiation). In addition to FRS3’s role in …

Identification Of A Molecular Opiate-Addiction Memory Switch In The Basolateral Amygdala, Danika C.A. Lyons

Electronic Thesis and Dissertation Repository

The molecular mechanisms involved in acquiring opiate-related associative memories are largely unknown. One neural region implicated in the formation of opiate-related memories is the basolateral nucleus of the amygdala (BLA). Transmission through dopamine (DA) receptors within the BLA controls the formation of opiate-related reward memories (Lintas et al., 2011; Lintas et al., 2012). Specifically, transmission through DA D1 receptors controls opiate reward memory formation in animals that are previously naïve to opiate exposure. However, once opiate dependence and withdrawal are present, intra-BLA DA-mediated control of opiate reward memory processing switches to a DA D2 receptor substrate. These findings demonstrate a …

Symbolizing Number: Fmri Investigations Of The Semantic, Auditory, And Visual Correlates Of Hindu-Arabic Numerals, Ian Douglas Holloway

Electronic Thesis and Dissertation Repository

Humans are born with a sensitivity to numerical magnitude. In literate cultures, these numerical intuitions are associated with a symbolic notation (e.g..Hindu-Arabic numerals). While a growing body of neuroscientific research has been conducted to elucidate commonalities between symbolic (e.g. Hinud-Arabic numerals) and non-symbolic (e.g. arrays of objects) representations, relatively little is known about the neural correlates specific to the symbolic processing of numerical magnitude. To address this, I conducted the three fMRI experiments contained within this thesis to characterize the neuroanatomical correlates of the auditory, visual, audiovisual, and semantic processing of numerical symbols.

In Experiment 1, the neural correlates of …

Brain Connectivity Studied By Fmri: Homologous Network Organization In The Rat, Monkey, And Human, R. Matthew Hutchison

Electronic Thesis and Dissertation Repository

The mammalian brain is composed of functional networks operating at different spatial and temporal scales — characterized by patterns of interconnections linking sensory, motor, and cognitive systems. Assessment of brain connectivity has revealed that the structure and dynamics of large-scale network organization are altered in multiple disease states suggesting their use as diagnostic or prognostic indicators. Further investigation into the underlying mechanisms, organization, and alteration of large-scale brain networks requires homologous animal models that would allow neurophysiological recordings and experimental manipulations. My current dissertation presents a comprehensive assessment and comparison of rat, macaque, and human brain networks based on evaluation …

Placental Insufficiency Resulting In Fetal Growth Restriction Alters Synaptic Development And Neuronal Myelination In Guinea Pigs At Term, Karolina Piorkowska

Electronic Thesis and Dissertation Repository

Aberrant neuronal connectivity in utero may underlie the association between fetal growth restriction (FGR) and increased risk for later cognitive disorders and encephalopathy. This study examines changes in synaptic development and myelination focussing on the hippocampus using a guinea pig model of placental insufficiency. Placental insufficiency was induced at mid-gestation by uterine artery ligation or cauterization which produced fetuses with a range of body weight and proportion at term. Synaptic markers, synaptophysin and synaptopodin, were decreased in FGR animals suggesting fewer synapses were formed and furthermore that fewer synapses matured with symmetrical growth restriction when compared to appropriate for gestational …

Toward A Functional Characterization Of Cognitive Control Networks, Frederick Ezekiel

Electronic Thesis and Dissertation Repository

Cognitive control is an executive process that has been associated with a distributed set of cortical regions. These distributed regions appear to cluster into distinct networks with dissociable functions. In this study, independent component analysis was used as a tool to investigate functional connectivity in event-related fMRI data. Extracted networks of interest were functionally characterized using a hybrid task that independently probed moment-to-moment adjustments in control, and stable task-set maintenance. A cinguloinsular network was implicated in the processing of moment-to-moment adjustments in control based on its activation patterns during this task. Subsequently, functional connectivity between two networks previously implicated in …

Top-Down Modulation Of Category Specific Extrastriate Cortex In A Task-Switching Paradigm, Katie Knapp

Electronic Thesis and Dissertation Repository

During selective attention, visual stimuli compete for processing capacity. Increased activation is found in extrastriate regions that represent the attended stimulus. However, little research has been done looking at activation in extrastriate regions when attention is shifted between stimulus features. To address this, participants completed a switching task during fMRI scanning. They attended to the colour or motion of bivalent stimuli on different trials. It was hypothesized that attentional modulation would be seen in colour area V4 and motion area V5 and that this modulation would help explain switch costs, a term used to describe why we are slower and …

Altered Auditory Feedback Causing Changes In The Vowel Production Of Children With Specific Language Impairment, Emily Michaela Holmes

Electronic Thesis and Dissertation Repository

Specific language impairment (SLI), an unexpected delay in the onset or development of oral language, has been hypothesized to have an underlying auditory processing component. Auditory feedback is a mechanism by which an individual controls the characteristics of their own voice, thereby assisting in the processing and production of speech. These characteristics include intensity, frequency, speed and others. The present study examined whether children with SLI make different use of auditory feedback than their typically developing (TD) peers. Participants aged 6-11 years completed a hearing screening, a frequency resolution task, vowel space task and a formant shifted auditory feedback task. …

Resting-State Connectivity Identifies Distinct Functional Networks In Macaque Cingulate Cortex., R Matthew Hutchison, Thilo Womelsdorf, Joseph S Gati, L Stan Leung, Ravi S Menon, Stefan Everling

Physiology and Pharmacology Publications

Subregions of the cingulate cortex represent prominent intersections in the structural networks of the primate brain. The relevance of the cingulate to the structure and dynamics of large-scale networks ultimately requires a link to functional connectivity. Here, we map fine-grained functional connectivity across the complete extent of the macaque (Macaca fascicularis) cingulate cortex and delineate subdivisions pertaining to distinct identifiable networks. In particular, we identified 4 primary networks representing the functional spectrum of the cingulate: somatomotor, attention-orienting, executive, and limbic. The cingulate nodes of these networks originated from separable subfields along the rostral-to-caudal axis and were characterized by positive and …

Synaptic And Systems Memory Consolidation In The Black-Capped Chickadee (Poecile Atricapillus), Matthew Barrett

Electronic Thesis and Dissertation Repository

ABSTRACT

Memory consolidation - the time-dependent stabilization of information- involves two processes: 1) synaptic consolidation and 2) systems consolidation. Synaptic consolidation uses a series of protein synthesis cascades that make lasting changes in the underlying neural architecture of a memory. Systems consolidation involves the reorganization of memory such that, with the passage of time, memory that is initially hippocampus-dependent can be retrieved and activated independent of the hippocampus. Black-capped chickadees (Poecile atricapillus) store and relocate food using hippocampus-dependent spatial memory. In Chapter 2 inhibition of protein synthesis by anisomycin, either 0 and 2 h or 4 and 6 …