Neuroscience and Neurobiology Commons^™

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 …

Septal Modulation Of The Hippocampus, Siew Kian Tai

Electronic Thesis and Dissertation Repository

The medial septum (MS) is the main source of acetylcholine to the hippocampus, a structure involved in memory and Alzheimer’s disease (AD). Learning and memory involve long-term changes in synaptic strengths, and are suggested to be facilitated by a brain wave, theta rhythm in the hippocampus. Since medial septal neurons influence hippocampal neural activity, lesion of two neuronal populations in the MS, cholinergic and GABAergic, was performed by intraseptal infusion of 192 IgG-saporin and orexin-saporin, respectively. I hypothesized that 1) activation of cholinergic cells by vestibular stimulation induces an atropine-sensitive theta rhythm, modulates synaptic transmission and enhances long-term potentiation (LTP), …

Effects Of Methamphetamine On Sexual Behavior, Karla S. Frohmader

Electronic Thesis and Dissertation Repository

Methamphetamine (Meth) is a highly addictive psychostimulant associated with enhanced sexual desire, arousal, and sexual pleasure. Moreover, Meth abuse is frequently linked with the practice of sexual risk behavior and increased prevalence of Human Immunodeficiency Virus (HIV). Currently, the neurobiological basis for this drug-sex nexus is unknown. Moreover, there is a lack of studies investigating the effects of Meth on sexual behavior and more importantly, compulsive sex-seeking behavior, under controlled experimental settings in animal models. First, using immuhistochemistry for mating- and Meth-induced neural activation it was demonstrated that Meth administration in male rats activates neurons in brain regions of the …

A Model Of Intracellular Θ Phase Precession Dependent On Intrinsic Subthreshold Membrane Currents., L Stan Leung

Physiology and Pharmacology Publications

A hippocampal place cell fires at an increasingly earlier phase in relation to the extracellular theta rhythm as a rodent moves through the place field. The present report presents a compartment model of a CA1 pyramidal cell that explains the increase in amplitude and the phase precession of intracellular theta oscillations, with the assumption that the cell receives an asymmetric ramp depolarization (<10 >mV) in the place field and rhythmic inhibitory and/or excitatory synaptic driving. Intracellular subthreshold membrane potential oscillations (MPOs) increase in amplitude and frequency, and show phase precession within the place field. Theta phase precession and MPO power …

Decoding Motor Intentions From Human Brain Activity, Jason P. Gallivan

Electronic Thesis and Dissertation Repository

“You read my mind.” Although this simple everyday expression implies ‘knowledge or understanding’ of another’s thinking, true ‘mind-reading’ capabilities implicitly seem constrained to the domains of Hollywood and science-fiction. In the field of sensorimotor neuroscience, however, significant progress in this area has come from mapping characteristic changes in brain activity that occur prior to an action being initiated. For instance, invasive neural recordings in non-human primates have significantly increased our understanding of how highly cognitive and abstract processes like intentions and decisions are represented in the brain by showing that it is possible to decode or ‘predict’ upcoming sensorimotor …

Dissociable And Dynamic Components Of Cognitive Control: A Developmental Electrophysiological Investigation, Matthew Waxer

Electronic Thesis and Dissertation Repository

One standard task used to investigate the development of cognitive control is the Dimensional Change Card Sort (DCCS). Performance and patterns of brain activity associated with the DCCS show continued age-related advances into early adolescence. According to many theoretical accounts, the DCCS places demands on a single underlying executive control process. Three experiments examined the possibility that the DCCS places demands on multiple control processes that follow distinct developmental trajectories. In Experiment 1, rule switching and conflict processing made orthogonal contributions to DCCS performance. Rule switching was associated with a cue-locked late frontal negativity (LFN) event-related potential (ERP) and conflict …

Perception Meets Action: Fmri And Behavioural Investigations Of Human Tool Use, Kenneth F. Valyear

Electronic Thesis and Dissertation Repository

Tool use is essential and culturally universal to human life, common to hunter-gatherer and modern advanced societies alike. Although the neuroscience of simpler visuomotor behaviors like reaching and grasping have been studied extensively, relatively little is known about the brain mechanisms underlying learned tool use.

With learned tool use, stored knowledge of object function and use supervene requirements for action programming based on physical object properties. Contemporary models of tool use based primarily on evidence from the study of brain damaged individuals implicate a set of specialized brain areas underlying the planning and control of learned actions with objects, distinct …

Regulation Of Akt And Wnt Signalling By The Dopamine D2 Receptor And Metabotropic Glutamate Receptor 2/3, Laurie P. Sutton

Electronic Thesis and Dissertation Repository

Akt and the Wnt pathway, two cascades that regulate GSK-3, have been implicated in schizophrenia and antipsychotic drug action. Although it is known that antipsychotic drugs alleviate psychosis by blocking the dopamine D2 receptor (D2DR) and that metabotropic glutamate receptor 2/3 (mGluR2/3) agonists may improve some of the symptoms of schizophrenia, it is unclear if both classes of drugs exert their effects through Akt, GSK-3 and/or the Wnt pathway or if changes in these pathways are mediated through the D2DR and mGluR2/3 respectively. In addition to antipsychotics, mood stabilizers and antidepressants also target GSK-3, suggesting that there must be something …

Mental Blocks: The Behavioural Effects And Neural Encoding Of Obstacles When Reaching And Grasping, Craig S. Chapman

Electronic Thesis and Dissertation Repository

The ability to adeptly interact with a cluttered and dynamic world requires that the brain simultaneously encode multiple objects. Theoretical frameworks of selective visuomotor attention provide evidence for parallel encoding (Baldauf & Deubel, 2010; Cisek & Kalaska, 2010; Duncan, 2006) where concurrent object processing results in neural competition. Since the end goal of object representation is usually action, these frameworks argue that the competitive activity is best characterized as the development of visuomotor biases. While some behavioural and neural evidence has been accumulated in favour of this explanation, one of the most striking, yet deceptively common, demonstrations of this capacity …

Seasonal Hippocampal Plasticity In Food-Storing Birds., David F Sherry, Jennifer S Hoshooley

Psychology Publications

Both food-storing behaviour and the hippocampus change annually in food-storing birds. Food storing increases substantially in autumn and winter in chickadees and tits, jays and nutcrackers and nuthatches. The total size of the chickadee hippocampus increases in autumn and winter as does the rate of hippocampal neurogenesis. The hippocampus is necessary for accurate cache retrieval in food-storing birds and is much larger in food-storing birds than in non-storing passerines. It therefore seems probable that seasonal change in caching and seasonal change in the hippocampus are causally related. The peak in recruitment of new neurons into the hippocampus occurs before birds …