Dissertations / Theses on the topic 'Behavioural neuroscience of learning and memory'
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Kwok, Sze Chai. "Mnemonic functions in the macaque monkey : further insight into the role of the fornix." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:a66d1d30-149d-4e12-801e-3944b08f4b1a.
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The fornical tract, a major input-output pathway of the hippocampus, of the primate brain makes crucial contributions to visual memory, as effects after surgical or aetiological lesions of this tract are widely documented in the monkey and human literature. Here, a series of experiments sought to further elucidate the functions of this structure with a battery of novel tasks in macaque monkeys, conducted either on a touchscreen or in an ambulatory chamber, so as to offer a more global view of the mnemonic role accomplished by it. After receiving bilateral transection of the fornix, monkeys are impeded in the 'fast learning' phase of a large number of new visuospatial conditional problems, with major impairments seen in eliminating non-perseverative errors. These fornix transected monkeys are however facilitated in the initial acquisition of a visuovisual conditional task, with facilitation seen in their improved ability in eliminating perseverative errors. It is also demonstrated in an ambulatory apparatus, in comparison to control monkeys, these monkeys are impaired in the new learning of visuospatial context of environments, albeit still displaying intact locomotor and exploratory behaviour patterns. Contrary to the relatively clear role in new learning, the involvement of the fornix in memory retention over the very long-term is unknown. It is shown here that once some visuospatial information is learnt; the fornix is no longer implicated in the retention of the material. The effects of fornix transection are also found to be detrimental on a spatial recognition task, with impairments observed in acquisition of the more demanding stages of the task. The overall results covered in this thesis support previous work suggesting that the fornix mediates the new learning of visual information, and I further propose that this fornical involvement lies primarily in the learning of spatio-temporal contexts, particularly during 'fast learning', as well as in task-sets acquisition. I also argue for dissociation in the contributions of the fornix and hippocampus to some memory processes in the macaque.
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Hoon, A. C. "The effect of manipulating the expression of the NR2B subunit of the NMDA receptor on learning and memory." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:eae324a3-873f-4b50-9bcc-8c43b72866a3.
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Overexpression of the NR2B subunit of the NMDA receptor in the forebrain has been shown to improve learning and memory in mice (Tang et al 1999), which provides exciting implications for the enhancement of human cognition. However, it was first essential to establish replicability, and since the Tang et al (1999) study used only male mice we wished to investigate possible sex differences. On the hidden platform watermaze, we found a trend for male NR2BOE mice to learn the task more quickly than male wildtype mice (as observed by Tang et al. 1999), but the opposite trend in female mice; female NR2BOE mice were slower to reach the hidden platform than female wildtype mice. This pattern of results was also observed on the spatial reference Y memory task and open field task (for anxiety), although not on the spatial working memory T maze task (despite a sex difference). However, wildtype and NR2BOE mice performed at similar levels on the novel object recognition task, the spatial novelty preference task, visible platform watermaze and visual discrimination task. A battery of tests considering some species typical behaviours of mice demonstrated that wildtype and NR2BOE mice were comparable on tests of motor ability, strength, co-ordination, anxiety, burrowing and nesting. This suggests that our behavioural results are not due to a general impairment or enhancement of species typical behaviours. We considered the possibility that the difference between the results of Tang et al (1999) and those we observed may be caused by age differences; hence we attempted to replicate our results on the hidden platform watermaze, spatial reference Y maze and open field test in age matched mice. However, the second cohort of NR2BOE mice performed at similar levels to wildtype mice, and at significantly improved levels compared to the mice of the first cohort. We also considered the effects of knocking out the NR2B subunit on learning and memory, and NR1 subunit deletion within the hippocampus. On the spatial working memory T maze, these mouse strains performed similarly to their respective wildtype strains. Similarly, on a two beacon watermaze (with one indicating the platform position), mice lacking the NR2B subunit were able to locate the platform in a similar length of time. To ensure that the null results we had observed in the second cohort were not due to loss of the NR2B protein overexpression in the forebrain, we performed polymerase chain reactions (PCR), quantitative real-time PCR, and Western blots. We ascertained that the transgene was indeed present and that NR2B mRNA and protein levels were elevated in the hippocampi of the NR2BOE mice. In conclusion, it is unclear why the behaviours we observed in the NR2BOE mice are different to those published in the literature. It is possible that they may be due to differences in environmental enrichment, but the cause of the genotype by sex differences observed in the mice of cohort 1 is unclear. Nonetheless, we have advanced our knowledge of the effects of modifications in the levels of the NR2B subunit of the NMDA receptor on learning and behaviour.
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Shipton, Olivia Ashley. "Asymmetry of hippocampal function in mice : left-right differences in memory processing and vulnerability to amyloid beta." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:972d7dbf-fcf1-4f84-9a84-406418dbc7fb.
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Amyloid beta (ABeta) and tau protein are both implicated in memory impairment in early Alzheimer’s disease, but whether and how they interact to cause synaptic dysfunction are unknown. Consequently, I firstly investigated whether tau protein is required for the robust phenomenon of ABeta-induced impairment of hippocampal long-term potentiation (LTP), a widely accepted cellular model of memory. I demonstrate that the absence of tau prevents the ABeta-induced impairment of LTP; moreover, a specific inhibitor of the tau kinase glycogen synthase kinase 3 blocks both an ABeta-induced increase in tau phosphorylation and the ABeta-induced LTP impairment. Thus, tau protein, likely in its phosphorylated form, is required for ABeta to impair LTP. Secondly, I investigated the underlying mechanisms for this ABeta-induced impairment and find that ABeta changes the balance between the two major types of glutamate receptors involved in plasticity processes, with a specific effect on GluN2B subunit-containing NMDA receptors. Since the distribution of these receptors is asymmetric between the left and right mouse hippocampus, I accessed these different types of synapses optogenetically and found that only the GluN2B-rich synapses receiving left CA3 input show ABeta-induced changes in the balance of glutamate receptors, suggesting an asymmetry in synaptic vulnerability to ABeta. Moreover, there was a left-right difference in tetanus-induced LTP and therefore, thirdly, I investigated whether mice have a hemispheric dissociation in memory processing using acute optogenetic silencing of left or right CA3 during hippocampus-dependent memory tasks. Unilateral silencing of either the left or the right CA3 caused a deficit in short-term memory, but only left CA3 silencing impaired performance on a spatial long-term memory task. Together, these results suggest that memory may be routed via distinct left-right pathways within the mouse hippocampus, and that neural pathways subserving distinct functions may also be differentially vulnerable to pathological changes at the synaptic level.
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Lee, Aletheia. "Site-directed monoclonal antibodies : developing a tool for manipulating AMPA-type ionotropic glutamate receptor subunits in the mouse brain." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:aa83582e-d096-4b0b-be6f-55a74fb16014.
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Ionotropic glutamate AMPA-type receptors mediate fast excitatory neurotransmission in the central nervous system and are essential for synaptic plasticity. Expression of the receptor subunits varies with cell type, stage of development and brain region. Subunit composition determines functional properties of the receptor, including gating kinetics and synaptic trafficking. The research aimed to selectively disrupt the GluA1 subunit abundantly expressed in the hippocampus of the wild-type mouse, so as to examine its role in learning and memory. Site-directed monoclonal antibodies were engineered to target the extracellular amino-terminal domain of GluA1 for subunit-selective manipulation. The antibody-binding region was selected for heterogeneity and accessibility based on the amino acid sequences and crystal structures solved for the AMPA receptor subunits. Immunisations of peptide antigen in mice generated serum antibodies that recognise the equivalent epitope on the fully folded GluA1 subunit. The antigen-binding Fab fragment of the monoclonal anti-GluA1 antibody was cloned from hydridoma mRNA and purified from large-scale transient expression in mammalian cells. Biophysical characterisations of anti-GluA1 Fab immunoglobulin showed high specificity and affinity for the target subunit. Acute bilateral intrahippocampal administration of anti-GluA1 Fab protein into awake, behaving wild-type mice produced dissociations in spatial memory performance that resembled GluA1-/- knockout mice. Impaired short-term spatial working memory but intact long-term spatial reference memory observed with anti-GluA1 Fab infusions suggested that the immunoglobulin reagent exerted an acute, reversible, localised, GluA1-specific antagonism in the brain. The findings argue for a critical involvement of the hippocampal GluA1 subunit in certain short-term memory processes, but not in other distinct long-term memory processes. Temporal resolution of the antibody-mediated disruption revealed novel fractionations of short-term memory performance never before observed in the GluA1-/- knockout mice, demonstrating the strength of the monoclonal anti-GluA1 antibodies as an investigative tool.
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Laatikainen, Linda Maria. "The role of catechol-O-methyltransferase (COMT) in hippocampal function." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:d0c9e1fa-a052-4af7-aaff-00548365e024.
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Catechol-O-methyltransferase (COMT) metabolises catechol-containing compounds, including dopamine. The aim of this thesis was to investigate whether COMT is involved in hippocampal function. This thesis also explored the role of functional polymorphisms within the COMT gene in the pathogenesis of schizophrenia and schizophrenia-related phenotypes. First, as part of a study investigating the role of COMT in schizophrenia, human hippocampal COMT mRNA levels were shown to be neither altered in schizophrenia or bipolar disease, nor affected by COMT genotype. Hence, functional COMT polymorphisms do not appear to operate by altering gross COMT mRNA expression. Importantly, this study showed that COMT is expressed in the human hippocampus. Second, the role of COMT in hippocampal neurochemistry was explored by studying the effect of pharmacological COMT inhibition on catecholamines and metabolites in rat hippocampal homogenates, and extracellularly, using microdialysis. Both demonstrated that COMT modulates hippocampal dopamine metabolism. Thus, hippocampal COMT is of functional significance with respect to dopamine. Third, the effect of COMT inhibition on hippocampus-dependent behaviour was investigated. The results suggested a memory-enhancing effect of pharmacological COMT inhibition on hippocampus-dependent associative and non-associative forms of short-term memory in rats. In contrast, acute COMT inhibition appeared to have no effect on behavioural correlates of ventral hippocampal function i.e. anxiety-like behaviour. In summary, the expression of COMT mRNA in the human hippocampus, as well as the effect of COMT inhibition on rat hippocampal neurochemistry and hippocampus-dependent behaviour provide evidence for a functional role of COMT in the hippocampus. Moreover, changes in COMT activity alter hippocampal dopamine metabolism, which could be a potential mechanism for the role of COMT in hippocampus-dependent short-term memory.
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Hölscher, Christian. "Behavioural and pharmacological studies of memory formation in the domestic chick, Gallus domesticus." Thesis, Open University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385848.
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Etherington, Rachel. "The behavioural consequences of cortical cholinergic deafferentation." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305332.
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Kanso, Riam. "The effect of interpersonal power on cognitive processing : a behavioural and neural perspective." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:cdde1f31-890a-444e-85fe-09b09348fcf1.
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Interpersonal power, defined as the asymmetrical control over valued outcomes, has important effects on the way cognitive processing unfolds. This work explores the effect of power on basic cognitive processes, in addition to broader processes that appear at the level of social behaviour. I begin this thesis with an introductory chapter, followed by a chapter describing the theory and practice behind electro-encephalogram recordings. In Chapter 3, I explore the effect of power on attention selection using a task that requires the ability to focus or divide attention in space, while varying the amount of distractors. The results suggest that low-power participants (subordinates) are more susceptible to the presence of distractors, regardless of whether the task necessitates focused or divided attention. In this context, inhibition accounts for the results to a greater extent than spatial orienting. In Chapter 4, I explore the effect of power on early inhibition processes in the context of executive control, in a task which allows participants to allegedly observe each others’ performance and receive feedback. The results show that high power is associated with reduced behavioural accuracy on trials that require executive control. Event-related potential analyses show that power-holders devote reduced motivational resources to their targets compared to subordinates, but do not differ at the level of early conflict detection. Their feedback potential results show a greater expectation of rewards, but reduced subjective magnitude attributed to losses. Subordinates, on the other hand, are asymmetrically sensitive to power-holders’ targets. They expect fewer rewards, but attribute greater significance to losses. In Chapter 5, I show that subordinates are asymmetrically competent at remembering diagnostic choices made by power-holders. In a final general discussion chapter, I integrate the findings of the experiments, which point to multi-layered effects of power, conferring those who possess it and those who lack it with distinct cognitive processing styles that suit their adaptive needs. The results are consistent with a hypothesized link between subordination and up-regulation of vigilance and environmental sensitivity. Limitations and future directions are discussed.
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Richter, Franziska Rebekka. "The control of task sets and long-term memory." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:6537ad2c-107b-4517-8b37-7d5d59edbe3b.
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The current thesis explores the complex relationship between cognitive control and memory. A series of experiments combined task-switching paradigms with recognition memory tests to measure how switching between tasks influences effective control over long-term memory. In these experiments, participants were presented with compound stimuli consisting of a picture and an overlaid word, and were cued in each trial whether the word or the picture was relevant (attended) or irrelevant (unattended). Participants were then tested for their memory of items presented during task switching. Experiments 1-2 indicated that switching between tasks reduces the selectivity of processing: Switching was associated with impaired task performance as well as more similar memory ratings for attended and unattended items. Experiments 3-5 extended these findings by showing that enhanced top-down control positively affected task-performance as well as memory, in both cases by increasing the selectivity of processing toward task-relevant information. Experiments 6-7 replicated key effects with simple switches of visual attention, and explored the neural correlates of successful task performance and encoding using EEG. The key finding here was that previously observed ―subsequent memory‖ effects reflect, at least in part, selective encoding processes. The last chapter extended the focus of the investigation to explore the role of control in long-term memory retrieval. FMRI meta- analyses indicated considerable overlap in neural activation found during task switching and during the adoption of different retrieval sets. The results of Experiment 8 indicated that switching during task performance and later memory retrieval were both associated with decreased selectivity of processing. Collectively, the results of this thesis suggest that selectivity of processing is a critical factor in effective task performance and successful memory, with potentially very similar mechanisms underlying the two. This work demonstrates the fruitfulness of combining research on cognitive control and memory to study questions relevant for both fields.
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Quinn, Connor. "Learning to read : effects of memory consolidation on orthographic and lexical learning." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278394.
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In recent years the role of offline consolidation in supporting word learning has attracted great interest and has provided valuable insight into how novel spoken and written words are learned. Relatively little attention has focused on whether offline consolidation supports the learning and generalisation of novel orthographic knowledge. Meanwhile, laboratory-based approaches have proven valuable in overcoming the methodological challenges of studying reading acquisition, i.e. learning letter-sound knowledge. This thesis combines laboratory-based orthographic learning with an overnight consolidation framework to track the effects of sleep on learning novel letters and novel written words in six experiments. Experiment 1 validated the artificial orthography paradigm by using fMRI to show the novel orthography activated similar neural regions to pseudowords written in familiar orthography. Comparing recently learned words and objects additionally highlighted the componential and holistic processes that distinguish reading from object naming. Experiments 2, 3, and 4 investigated whether overnight consolidation had contrasting effects on learning novel letters and learning novel written words. All three studies showed overnight improvements in the ability to use and generalise knowledge of letters. Experiment 3 further assessed whether consolidation supported the formation of bigram representations. While the results did not show bigram consolidation, a recognition memory task indicated participants had consolidated the novel spoken words. Experiment 4 manipulated the internal statistical structure of the novel words finding, in contrast to Experiment 3, participants had consolidated the written forms of the novel words. Experiments 5 and 6 asked whether consolidated and unconsolidated spoken words would support orthographic learning. These studies failed to observe previous findings of spoken word consolidation and did not demonstrate clear effects of lexical knowledge on orthographic learning. The findings of the thesis demonstrate the importance of letter-level learning and consolidation during reading acquisition as well as highlighting the value of laboratory-based studies for understanding the interdependent trajectories of the skills involved in reading.
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Kwon, Hyung-Wook. "Learning and memory in the American cockroach, Periplaneta americana: New behavioral paradigms for associative learning." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280108.
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Although there is much information about insect associative learning, less is known about the underlying neural mechanisms. This is partly due to the lack of behavioral paradigms providing a suitable model for studying learning mechanisms at the level of individual neurons. This thesis describes the background to, and the demonstration of, two associative learning paradigms: visual associative learning and spatial learning. Both have been developed on the restrained cockroach so that later these methods can be employed in conjunction with electrophysiology. By projecting their antennae intermittently towards a position of potential food sources, cockroaches sample salient information. Here, this antennal behavior, called an "antennal projection response (APR)," is used to demonstrate long-term memory where an APR is elicited by a conditioning stimulus (CS: green light) paired with a spatially coincident odor (unconditioned stimulus: US). The acquired APR to the green light cue persists for up to 72 hours. Spatial learning is also a vitally important behavior in most animals that must remember locations of food and landmarks and that must navigate. Spatial learning abilities were here tested by observing APRs towards a cue, where the cockroach learns the position of a visual cue (CS) associated with a food odor (US), relative to the position of another visual stimulus in the contralateral visual field (the contralateral visual reference stimulus: ConRS). Memory of positional information, tested by altering the relative positions of the CS and ConRS, was investigated. Cockroaches showed significant APRs to visual cues not only when a position of the visual cue and spatial reference cue were exactly matched during training trials, but also during tests when the relative angles between the visual cue and spatial reference cue were matched but rotated around the head's vertical axis. When these angles were not the same as the angle used for training, the CS was not recognized. These results suggest that cockroaches employ two different mechanisms to find a food source: retinotopic matching and recognition of angular relationships between a source and landmark. The application of these paradigms to studies that could investigate possible neural mechanisms of these behaviors is discussed.
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Wolff, Gabriella Hannah. "Genealogical Correspondence of Learning and Memory Centers across Phyla." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556847.
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Across bilaterian phyla, learning and memory allows animals to benefit from central-place foraging, return to ideal food sources, choose mates and avoid dangerous or harmful external stimuli. Although these behaviors are comparable in both vertebrate and invertebrate animals, it is unknown whether or not they are mediated by homologous brain structures. In insects, paired, lobate forebrain structures called mushroom bodies receive input from primary sensory neuropils and are necessary for learning and memory, whereas in crustaceans, this behavior is mediated by paired, compact forebrain structures called hemiellipsoid bodies. Mammalian learning and memory is mediated by the paired, horn-shaped hippocampi, which also receive sensory input and are likewise situated in the forebrain. Did these structures evolve independently along with the ability for animals to learn and remember associations and places? Alternatively, the hypothesis posited in this dissertation is that the last bilaterian ancestor already possessed the ability to learn and adapt to its environment, behavior mediated by paired forebrain structures that evolved divergently into the elaborated forms we observe in extant, crown-group taxa. This hypothesis is investigated and discussed in the following reports: 1) a review of insect brain anatomy and functional connectivity, including a description of mushroom bodies, in the context of arthropod evolution; 2) a comparison of neuroanatomy, circuitry, and protein expression between insect mushroom bodies and Malacostracan crustacean hemiellipsoid bodies, using cockroaches and Caribbean hermit crabs as representatives of their classes; 3) a deeper investigation of the fine structure of neuronal organization in the hemiellipsoid body of the Caribbean hermit crab, focusing on electron microscopical observations and comparisons to the ultrastructure of the fruit fly mushroom body; 4) a survey of four invertebrate Phyla, employing the strategy of comparing neuroanatomy and protein expression to investigate whether higher order forebrain structures in these animals were inherited from a common ancestor; 5) a comparison of neuroanatomy, connectivity, and protein expression in insect mushroom bodies and mammalian hippocampus, including a survey of PKA-Cα in these and corresponding structures across the Chordata. The total evidence suggests that a common Bilaterian ancestor possessed a center that evolved to become mushroom bodies in invertebrates and hippocampus in vertebrates.
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Shen, Jiemin 1968. "The aging hippocampus: Neural mechanisms underlying learning and memory deficits in old rats." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290678.
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This dissertation focuses on the effect of aging on two functional aspects of rat hippocampus: cholinergic synaptic transmission and place specific firing of CA1 pyramidal cells. The effect of age on the cholinergic slow EPSP was studied in hippocampal slices of young, adult and old rats. The old rats were impaired on the spatial version of the Morris water task. The amplitude of the slow EPSP was significantly reduced in old rats in all hippocampal subregions (CA1 59%; CA3 55%; and DG 56%). Few statistically significant correlations, however, were found between the age-related deficit in spatial learning and the cholinergic deficit. In the subsequent study, effects of selective neurotoxic lesions of cholinergic afferents to the hippocampus on performance on two versions (spatial working memory and spatial reference memory) of the radial-8-arm maze task were examined. The lesioned rats were impaired in acquisition, but not retention, of the working memory task. There was no treatment effect, however, on acquisition of the reference memory task. The results suggest that the age-related deficits in hippocampal cholinergic function may contribute to behavioral deficits of old rats in working memory situations, but may not be primarily responsible for the spatial reference memory problem in the Morris water task. The spatial and temporal firing characteristics of CA1 neurons were studied in young and old rats performing a simple spatial task on a rectangular track. The average place fields of young rats were larger than those of old rats. Precession of spike discharge relative to the theta rhythm proceeded faster in old rats, while the total phase change remained constant. These age-related changes were apparently due to a loss of experience dependent place field expansion of old rats during the first few laps around the track for a given recording session. The field sizes were not different between groups on lap 1. Because experience-dependent place field expansion is a prediction of two recent theories which invoke asymmetric Hebbian LTP, the present observations point towards a substantial deficit in an LTP-like process in old rats.
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Pritchett, David. "Sleep, circadian and behavioural characterisation of two schizophrenia-relevant transgenic mouse models." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:1853944f-8ee1-4ed8-9214-d8a61c6bb46d.
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Border, Scott. "Investigating the role of macromolecules in learning and memory using a behavioural boiassay." Thesis, Oxford Brookes University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432788.
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Sziklas, Viviane. "Behavioural investigation of the mammillary region in the rat." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70274.
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The experiments reported in the present dissertation investigated the contribution of the mammillary region to several classes of learning and memory: spatial memory, nonspatial memory, and conditioned aversion learning. It was demonstrated that such lesions impair performance on tasks that require memory for spatial information but that the deficit depends on both the amount of damage within the region as well as the degree of difficulty of the task. A dissociation in the effect of such lesions on performance of comparable spatial and nonspatial memory tasks was shown. In contrast to the severe deficits observed on spatial memory tasks, the acquisition and retention of a complex nonspatial memory task was not impaired after extensive damage to the mammillary region. Such lesions also did not impair performance on two conditioned aversion tasks. These experiments suggest that the mammillary region may be selectively involved in spatial learning and memory. The relevance of these findings to Korsakoff's syndrome is discussed.
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Chau, Ka Hung Bolton. "Neural mechanisms of suboptimal decisions." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:67c43f70-a7fa-40b1-9691-bb520d5f9e2d.
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Making good decisions and adapting flexibly to environmental change are critical to the survival of animals. In this thesis, I investigated neural mechanisms underlying suboptimal decision making in humans and underlying behavioural adaptation in monkeys with the use of functional magnetic resonance imaging (fMRI) in both species. In recent decades, in the neuroscience of decision making, there has been a prominent focus on binary decisions. Whether the presence of an additional third option could have an impact on behaviour and neural signals has been largely overlooked. I designed an experiment in which decisions were made between two options in the presence of a third option. A biophysical model simulation made surprising predictions that more suboptimal decisions were made in the presence of a very poor third alternative. Subsequent human behavioural testing showed consistent results with these predictions. In the ventromedial prefrontal cortex (vmPFC), I found that a value comparison signal that is critical for decision making became weaker in the presence of a poor value third option. The effect contrasts with another prominent potential mechanism during multi-alternative decision making – divisive normalization – the signatures of which were observed in the posterior parietal cortex. It has long been thought that the orbitofrontal cortex (OFC) and amygdala mediate reward-guided behavioural adaptation. However, this viewpoint has been recently challenged. I recorded whole brain activity in macaques using fMRI while they performed an object discrimination reversal task over multiple testing sessions. I identified a lateral OFC (lOFC) region in which activity predicted adaptive win-stay/lose-shift behaviour. In contrast, anterior cingulate cortex (ACC) activity predicted future exploratory decisions regardless of reward outcome. Amygdala and lOFC activity was more strongly coupled for adaptive choice shifting and decoupled for task irrelevant reward memory. Day-to-day fluctuations in signals and signal coupling were correlated with day-to-day fluctuations in performance. These data demonstrate OFC, ACC, and amygdala each make unique contributions to flexible behaviour and credit assignment.
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Clark, Ian Alexander. "A clinical neuroscience investigation into flashbacks and involuntary autobiographical memories." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:04f72e37-73fe-4347-8af1-8d8852c05f1b.
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Recurrent and intrusive distressing recollections of trauma are a hallmark symptom of Posttraumatic Stress Disorder (PTSD). The term ‘flashback’ is used in this thesis to refer to vivid, sensory perceptual (predominantly visual images), emotional memories from a traumatic event that intrude involuntarily into consciousness. Furthermore, intrusive image based memories occur in a number of other psychological disorders, for example, bipolar disorder and depression. Clinically, the presence and occurrence of flashbacks and flashback type memories are well documented. However, in terms of the neural underpinnings there is limited understanding of how such flashback memories are formed or later involuntarily recalled. An experimental psychopathology approach is taken whereby flashbacks are viewed on a continuum with other involuntary autobiographical memories and are studied using analogue emotional events in the laboratory. An initial review develops a heuristic clinical neuroscience framework for understanding flashback memories. It is proposed that flashbacks consistent of five component parts – mental imagery, autobiographical memory, involuntary recall, attention hijacking and negative emotion. Combining knowledge of the component parts helped provide a guiding framework, at both a neural and behavioural level, into how flashback memories may be formed and how they return to mind unbidden. Four studies (1 neuroimaging, 3 behavioural) using emotional film paradigms were conducted. In the first study, the trauma film paradigm was combined with neuroimaging (n = 35) to investigate the neural basis of both the encoding and the involuntary recall of flashback memories. Results provided a first replication of a specific pattern of brain activation at the encoding of memories that later returned as flashbacks. This included elevation in the rostral anterior cingulate cortex, insula, thalamus, ventral occipital cortex and left inferior frontal gyrus (during just the encoding of scenes that returned as flashbacks) alongside suppressed activation in the left inferior frontal gyrus (during the encoding of scenes that returned as flashbacks in other participants, but not that individual). Critically, this is also the first study to show the brain activation at the moment of flashback involuntary recall in the scanner. Activation in the middle and superior frontal gyri and the left inferior frontal gyrus was found to be associated with flashback involuntary recall. In the second study, control conditions from 16 behavioural trauma film paradigm experiments were combined (n = 458) to investigate commonly studied factors that may be protective against flashback development. Results indicated that low emotional response to the traumatic film footage was associated with an absence of flashbacks over the following week. The third study used a positive film to consider the emotional valence of the emotion component of the framework. Positive emotional response at the time of viewing the footage was associated with positive involuntary memories over the following week. The fourth study aimed to replicate and extend this finding, comparing the impact of engaging in two cognitive tasks after film viewing (equated for general load). Predictions were not supported and methodological considerations are discussed. Results may have implications for understanding flashbacks and involuntary autobiographical memories occurring in everyday life and across psychological disorders. Further understanding of the proposed components of the clinical neuroscience framework may even help inform targeted treatments to prevent, or lessen, the formation and frequency of distressing involuntary memories.
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Browncross, Helen Anna. "The role of the primate frontopolar cortex in mnemonic and choice behaviour." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:2807879b-e535-474c-b884-fa4c3c5296ab.
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The role of the primate frontopolar cortex (FPC) has been investigated using human neuroimaging, lesion and disruption techniques. The results of these investigations have led to a variety of theories regarding the function of this region. It has been linked to the formation of task sets, the performance of multiple tasks, reasoning, context-specific memory (including episodic memory, prospective memory and source memory), attention to internally or externally generated information, mentalising and decision-making. It has not previously been possible to study this area using animal lesion techniques. Here, behavioural experiments conducted using non-human primates (rhesus macaque monkeys) who have received lesions to the frontal pole investigate the contribution of this region to context-specific memory, decision-making and social cognition. Functional magnetic resonance imaging (fMRI) is used to investigate changes in functional network connectivity which occur after lesions to this region. A long-lasting impairment is observed in contextual memory judgements (specifically, how recently a stimulus was encountered) after lesions to the frontal pole. An analysis of the influence of the outcomes of previous choices on behaviour on an analogue to the Wisconsin Card Sorting Test (WCST) indicate that monkeys with lesions to area 10 may be less influenced by the outcomes of an extended history of rewards than control animals. Long-lasting widespread disruption to functional networks after lesions to this region indicate that indirect anatomical connections from this region to posterior areas play a crucial role in the normal functioning of posterior networks.
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Barber, Alistair John. "A behavioural investigation of the function of glycoprotein fucosylation in learning and memory in the day-old domestic chicken." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236514.
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Gudberg, Christel Alessandra. "Effects of age on sleep and consolidation of motor learning." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:4537a396-3947-4afb-be46-92105d17000a.
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Background: Our ability to consolidate what we learn changes with age. However, little is known about the neurophysiological underpinnings of consolidation of motor learning in ageing. This is largely because studies have repeatedly demonstrated a deficit in sleep-dependent consolidation of motor learning in older adults. This thesis aims to reassess commonly held assumptions about consolidation in ageing, as well as to examine the neurophysiological and neurochemical mechanisms that support the learning and consolidation processes. Methods: Most of the studies in this thesis are based on the design of a novel whole-hand task for use in older adults, which reduces dependency on fine motor skill. This thesis adopts a number of converging measures to examine learning and memory including electroencephalograhy (EEG), magnetic resonance spectroscopy (MRS), actigraphy recordings, as well as behavioural and self-reported measures of sleep. Results: Findings show significant improvements in learning with the adapted motor task in older adults. Importantly, this task reveals significant sleep- dependent enhancements in older adults, which are comparable to those seen in younger controls. Functional changes in sleep architecture with ageing show overall decline in slow wave sleep. Sleep-dependent improvements were specifically associated with activity in stage 3 slow wave sleep and increased hemispheric differences regardless of age. Changes in GABA concentrations with learning on a visuomotor tracking task showed marked variability across participants, and no clear associations were found between GABA and consolidation. Conclusion: The evidence presented in this thesis highlight the complex dynamics underlying sleep consolidation, and challenges a commonly held assumption about consolidation in older adults. Specifically, the studies presented here show that observed declines in motor consolidation with ageing may be contaminated by age-related deficits fine motor skill. By removing such kinematic constraints, it was possible to detect marked improvements in motor performance also in older adults despite age-related changes in sleep architecture.
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Desai, Avanti N. "Effects of Perinatal Polychlorinated Biphenyl Mixtures on Estrogen Receptor Beta, Hippocampus, and Learning and Memory." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1182713137.
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Coulson, Louisa Katie. "The influence of emotional stimuli on cognitive processing during transient induced mood states." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:b8fc9fab-e9e0-4b3f-b78e-c76e25224972.
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Selective attention is a mechanism used to allocate resources to information processing. Both mood states and emotionally salient stimuli can influence which information is selectively attended. This information is subsequently processed in a more elaborative manner and affects task performance. The experiments presented in this thesis explore the influence of mood and emotional stimuli on selective attention and consequently task performance. Mood induction procedures were used to induce transient neutral, sad, and happy mood states in healthy volunteers. A systematic review and meta-analysis of 41 studies using sad mood induction procedures showed cognitive impairments in performance in the context of task neutral stimuli. In contrast biases in attention towards mood-congruent negative stimuli led to improved task performance. A series of three behavioural experiments with 197 participants demonstrated that participants made decisions on the basis of less information when that information was preceded by emotional but not neutral stimuli. Induced mood state did not affect performance. The behavioural and neural correlates of visual attentional processing to emotional stimuli were explored using magnetoencephalography in 24 healthy participants following sad, happy, and neutral mood induction procedures. The M300, a component associated with selective attention, had greater amplitude following presentation of negative compared with positive stimuli, which was associated with improved task performance. Reduced M300 amplitude and impairments in performance occurred following sad mood induction procedures. The experiments presented in this thesis demonstrate prioritized processing of emotional information and provide some evidence for impaired performance following sad mood induction procedures.
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MacLeod, Lindsey. "Visual Spatial Learning and Memory in Fragile X Syndrome and fmr1 Knockout Mice." Thesis, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26001.
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This dissertation describes separate but related studies that explore visual spatial learning and memory in Fragile X Syndrome. Across all studies, either the performance of individuals affected by FXS and/or fmr1 KO mice was compared to comparison controls on seven H-W mazes of increasing difficulty levels. Study one employed the traditional configuration of the H-W mazes to evaluate performance variables that include latency to complete the maze and number of the errors. The results of study 1 revealed significant differences in performance for both FXS groups as compared to mental age-matched comparison individuals and wild type mice, respectively. In contrast to the FXS group, performance of the comparison group improved as indicated by significantly fewer errors across trials. A similar pattern of results was observed when latency across trials was analyzed. Taken together, the results of study one support the hypothesis that a selective deficit in spatial learning and memory characteristic of the FXS phenotype can be observed in the murine model of FXS, if equivalent tasks are employed in testing humans and mice.
Study two expanded on these findings by adding landmarks to the maze environment to evaluate how these may impact spatial learning and memory in fmr1 KO mice. Contrary to our hypotheses, landmarks significantly impaired wild type control performance. In addition, results revealed that the performance of the fmr1 KO mice generally did not differ between landmark and non-landmark tasks, indicating that the presence of landmarks neither enhanced nor hindered mouse performance.
Lastly, study three entailed a more in-depth behavior analysis of maze navigation performance for FXS individuals from study 1. Consistent with the hypotheses and findings from study 1, results revealed significant differences in performance variables between individuals, with FXS participants generally performing worse than the comparison group participants. Taken together, the results of study 3 generally supported the hypothesis that there was greater impairment in performance for individuals affected by FXS as compared to controls. This impairment was evident in the pattern of pathways taken to solve H-W mazes, consistent with the notion that affected individuals employed different behavioral strategies.
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Cosman, Joshua Daniel. "Task-specific learning supports control over visual distraction." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/2845.
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There is more information in the visual environment than we can process at a given time, and as a result selective attention mechanisms have developed that allow us to focus on information that is relevant to us while ignoring information that is not. It is often assumed that our ability to overcome distraction by irrelevant information in the environment requires conscious, effortful processing, and traditional theories of selective attention have emphasized the role of an observer's explicit intentions in driving this control. At the same time, effortful control on the basis of explicit processes may be maladaptive when the behaviors to be executed are complex and dynamic, as is the case with many behaviors that we carry out on a daily basis. One way to increase the efficiency of this process would be to store information regarding past experiences with a distracting stimulus, and use this information to control distraction upon future encounters with that particular stimulus. The focus of the current thesis was to examine such a "learned control" view of distraction, where experience with particular stimuli is the critical factor determining whether or not a salient stimulus will capture attention and distract us in a given situation. In Chapters 2 through 4, I established a role for task-specific learning in the ability of observers to overcome attentional capture, showing that experience with particular attributes of distracting stimuli and the context in which the task was performed led to a predictable decrease in capture. In Chapter 5, I examined the neural basis of these learned control effects, and the results suggest that neocortical and medial temporal lobe learning mechanisms both contribute to the experience-dependent modulation of attentional capture observed in Chapters 2-4. Based on these results, a model of attentional capture was proposed in which experience with particular stimulus attributes and their context critically determine the ability of salient, task-irrelevant information to capture attention and cause distraction. I conclude that although explicit processes may play some role in this process under some conditions, much of our ability to overcome distraction results directly from past experience with the visual world.
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Gage, Stephanie Lauren. "The Behavioral Significance of Nitric Oxide in a Primary Olfactory Network: Insights into Learning and Memory in the Antennal Lobe of Manduca Sexta." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/306943.
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Nitric oxide (NO) is a gaseous, unconventional chemical messenger suggested to play a fundamental role in olfaction. This thesis focuses on the role of NO in a primary olfactory center, the antennal lobe (AL) of the moth, Manduca sexta (M. sexta), to understand how NO affects olfactory-guided behavior. Studies in M. sexta report that NO is produced upon odor stimulation and has profound effects at the physiological level, but little is known about its significance to behavior. The central hypothesis examined in this thesis is that NO functions as a neuromodulator of olfactory-guided behavior in a circadian fashion. This hypothesis is examined in the following three studies: The first study questions whether basal levels of NO fluctuate with the light cycle. M. sexta are nocturnal animals that actively engage in odor-seeking behaviors at night. Using an NO sensor, NO concentrations were measured in the AL, optic lobe, and the remainder of the brain during subjective day and subjective night. NO concentrations are higher in the AL and optic lobes at night, suggesting that NO is likely involved in olfactory-guided behavior. The second inquiry focuses on developing a technique to manipulate NO levels in the AL and whether a specific behavior is affected. Using the proboscis extension reflex, olfactory conditioning is used to ask three questions: (1) does NO affect odor detection, (2) does NO affect discrimination between odorants, and (3) does NO affect learning and memory? Results indicate that NO affects short-term memory but does not affect odor detection, or discrimination between dissimilar odorants. The third inquiry examines the role of NO in memory and circadian time. It asks: (1) is there an optimal time of day for learning and memory, and (2) does the role of NO in memory change depending on the time of olfactory conditioning? Results indicate that NO in memory is modulated by circadian time. Taken together, these results suggest a unique functional role for NO in olfactory-guided behavior with two main conclusions: (1) NO modulates short-term memory in the AL, and (2) NO may be important for the circadian regulation of memory.
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Frazier, Hilaree N. "Exploring the Role of Insulin Receptor Signaling in Hippocampal Learning and Memory, Neuronal Calcium Dysregulation, and Glucose Metabolism." UKnowledge, 2019. https://uknowledge.uky.edu/pharmacol_etds/32.
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In the late 90’s, emerging evidence revealed that the brain is insulin-sensitive, highlighted by broad expression of brain-specific insulin receptors and reports of circulating brain insulin. Contemporary literature robustly supports the role of insulin signaling in normal brain function and suggests that insulin-related processes diminish with aging, evidenced by decreased signaling markers, reduced insulin receptor density, and lower levels of insulin transport across the blood-brain barrier. In the context of pathological cognitive decline, clinical trials using intranasal insulin delivery have reported positive outcomes on memory and learning in patients with mild cognitive decline or early-stage Alzheimer’s disease. However, while the importance of insulin and its related actions in the brain are robustly supported, the distinct mechanisms and pathways that mediate these effects remain unclear.
To address this, I conducted a series of experiments exploring the impact of insulin on memory and learning in two models: primary hippocampal cell cultures and the Fisher 344 animal model of aging. These studies attempted to identify relationships between insulin receptor signaling, neuronal gene expression, glucose metabolism, and calcium homeostasis in the hippocampus using either expression of a constitutively active human insulin receptor or administration of intranasal insulin. The following dissertation summarizes this work and provides valuable insights into the potential pathways mediating these relationships. Of note, intranasal studies reported that insulin is able to significantly alter gene expression patterns in the hippocampus of both young and aged rats following chronic, repeated exposure to the ligand. In cell culture, constitutive insulin signaling correlated with significantly elevated neuronal glucose uptake and utilization, as well as with significant alterations in the overall expression and localization of the neuron-specific glucose transporter 3. Interestingly, continued activity of the insulin receptor did not appear to alter voltage-gated calcium channels in hippocampal neurons despite prior evidence of the ligand’s role in other calcium-related processes.
The results reported in this manuscript suggest that in the brain, insulin may be involved in a myriad of complex and dynamic events dependent on numerous variables, such as age, length of the exposure, and/or the insulin formulation used. Nevertheless, this work highlights the validity of using insulin to ameliorate age-related cognitive decline and supports the need for further studies exploring alternative approaches to enhance insulin receptor signaling in the brain.
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Jackson, Taryn. "Molecular and Genetic Analysis of Synaptic Signaling in Drosophila." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1356%5F1%5Fm.pdf&type=application/pdf.
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Dhawan, Sandeep Sonny. "Learning to focus and focusing to learn : more than a cortical trick." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/15883.
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The consequence of many psychiatric and neurodegenerative disorders, such as Parkinson's disease and schizophrenia, is an impairment in ‘executive functioning'; an umbrella term for several cognitive processes, including the focussing and shifting of attention and the inhibition of responding. The ability to form an ‘attentional set' involves learning to discriminate qualities of a multidimensional cue, and to subsequently learn which quality is relevant, and therefore predictive of reward. According to recent research, the subthalamic nucleus (STN) and possibly the adjacent zona incerta (ZI) may mediate the formation of attentional set. Dysregulation of the STN as a result of Parkinson's disease contributes to characteristic motor symptoms, and whilst deep-brain stimulation of this region may treat gross motor impairments, it may also impair cognition. The work in this thesis aimed to expand our understanding of the mechanisms of attentional set-formation, and the role of the STN in this process. This thesis evaluates new methods for examining set-formation in the attentional set-shifting task; rather than inferring this behaviour solely from the cost of shifting set, modifications to the task design in Chapters 3 & 4 explored several hypotheses designed to exploit a deficit in this behaviour. Chapter 6 revealed that inhibition of this region with designer receptors leads to a disruption in attentional selectivity, which compromises the ability to form an attentional set. This manifested as an inability to parse relevant information from irrelevant, and instead, animals learned the stimuli holistically. The findings in this thesis also suggested that reversal and attentional shifting processes do not operate independently, but rather in a hierarchy, and that consequently, the STN is a region that may be crucial in selecting appropriate responses during associative learning that leads to the formation of an attentional set.
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Aguiar, Sebastian. "Characterizing a Novel Monoclonal AMPA Receptor 1/2/3 Antibody in the Hippocampus and Prefrontal Cortex of Rat, Monkey, and Human." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/pitzer_theses/82.
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The excitatory, ionotropic glutamatergic AMPA receptor is the most common membrane-bound receptor in the central nervous system. AMPARs and the NMDA receptors are central to synaptic plasticity, memory, and mechanisms of neurodegeneration. The AMPAR is an obligate heterotetramer, composed of subunits GluA1-4. Subunit permutation determines ion conductance, trafficking and other functional characteristics. Few available antibodies are subunit-specific, disabling researchers from accurately visualizing differential AMPAR subunit distribution in the nervous system. This study sought to visualize a novel monoclonal GluA1/2/3 antibody with functional avidity for three of four receptor subunits and to characterize the ultrastructural localization of these receptors using confocal and electron microscopy.
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Gulick, Danielle. "An Examination of the Neural Substrates Underlying the Dissociable and Interactive Effects of Acute Ethanol and Nicotine on Learning, Anxiety, and Locomotion in Fear Conditioning and the Plus Maze Discriminative Avoidance Task." Diss., Temple University Libraries, 2008. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/18921.
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PsychologyPh.D.
Studies have demonstrated dissociable effects of nicotine alone versus in combination with ethanol on learning, and these effects may depend on different neural substrates. Furthermore, the effects of nicotine in different brain areas may produce other behavioral changes - such as changes in anxiety - that alter learning. This research examines the interactive effects of ethanol and nicotine on learning, anxiety, and locomotion, and the dissociation of these effects by brain area. Specifically, we examine the interactive effects of systemic ethanol with nicotine infusion into the dorsal hippocampus, ventral hippocampus, or anterior cingulate on contextual and cued fear conditioning and the plus-maze discriminative avoidance task (PMDAT). In addition, we use dihydro-beta-erythroidine (DHbetaE), a nicotinic receptor antagonist, to examine the involvement of acetylcholingeric nicotinic receptors (nAChRs) in the effects of ethanol alone and in the mediation of ethanol-induced changes by nicotine. In the PMDAT, we examine whether caffeine produces the same effects as nicotine in the PMDAT. In fear conditioning, nicotine acts in the dorsal hippocampus to enhance contextual fear conditioning and in the anterior cingulate to reverse ethanol-induced contextual and cued fear conditioning deficits through inactivation of high-affinity beta2 subunit-containing nAChRs. In the PMDAT, ethanol produces learning deficits, anxiolysis, and increased locomotion, and nicotine reverses the effects of ethanol. Although caffeine and ethanol interact to modulate behavior in the PMDAT, caffeine fails to reverse ethanol-induced learning deficits. Finally, the effects of nicotine and ethanol, both alone and in combination, on learning, anxiety, and locomotion depend on distinct neural substrates. Nicotine acts in the anterior cingulate to reverse ethanol-induced learning deficits but produces diverse effects on anxiety that vary across all three brain areas.
Temple University--Theses
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Barkus, Christopher. "Studies of emotionality in genetic mouse models of altered glutamate or 5-HT function." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:c144d0d0-ba1f-4127-b07a-372e6abf569b.
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Rehn, Martin. "Aspects of memory and representation in cortical computation." Doctoral thesis, KTH, Numerisk Analys och Datalogi, NADA, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4161.
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Denna avhandling i datalogi föreslår modeller för hur vissa beräkningsmässiga uppgifter kan utföras av hjärnbarken. Utgångspunkten är dels kända fakta om hur en area i hjärnbarken är uppbyggd och fungerar, dels etablerade modellklasser inom beräkningsneurobiologi, såsom attraktorminnen och system för gles kodning. Ett neuralt nätverk som producerar en effektiv gles kod i binär mening för sensoriska, särskilt visuella, intryck presenteras. Jag visar att detta nätverk, när det har tränats med naturliga bilder, reproducerar vissa egenskaper (receptiva fält) hos nervceller i lager IV i den primära synbarken och att de koder som det producerar är lämpliga för lagring i associativa minnesmodeller. Vidare visar jag hur ett enkelt autoassociativt minne kan modifieras till att fungera som ett generellt sekvenslärande system genom att utrustas med synapsdynamik. Jag undersöker hur ett abstrakt attraktorminnessystem kan implementeras i en detaljerad modell baserad på data om hjärnbarken. Denna modell kan sedan analyseras med verktyg som simulerar experiment som kan utföras på en riktig hjärnbark. Hypotesen att hjärnbarken till avsevärd del fungerar som ett attraktorminne undersöks och visar sig leda till prediktioner för dess kopplingsstruktur. Jag diskuterar också metodologiska aspekter på beräkningsneurobiologin idag.In this thesis I take a modular approach to cortical function. I investigate how the cerebral cortex may realise a number of basic computational tasks, within the framework of its generic architecture. I present novel mechanisms for certain assumed computational capabilities of the cerebral cortex, building on the established notions of attractor memory and sparse coding. A sparse binary coding network for generating efficient representations of sensory input is presented. It is demonstrated that this network model well reproduces the simple cell receptive field shapes seen in the primary visual cortex and that its representations are efficient with respect to storage in associative memory. I show how an autoassociative memory, augmented with dynamical synapses, can function as a general sequence learning network. I demonstrate how an abstract attractor memory system may be realised on the microcircuit level -- and how it may be analysed using tools similar to those used experimentally. I outline some predictions from the hypothesis that the macroscopic connectivity of the cortex is optimised for attractor memory function. I also discuss methodological aspects of modelling in computational neuroscience.
QC 20100916
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Porcheret, Kate L. "Sleep and sleep timing in relation to light and emotional processing." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:b759244a-c339-4d9f-bd03-e150a5fa1887.
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Sleep is a complex process: the timing of sleep is regulated by two systems (the sleep homeostat and the circadian clock) and there are many potential functions of sleep. The aim of this thesis was to investigate: the impact of light on the regulation of sleep timing (study 1) and the role of sleep in emotional processing (study 2). Study 1 used natural variations in environmental light levels at different geographical locations, to examine the influence of daily light irradiance on sleep timing and chronotype using the Munich chronotype questionnaire (MCTQ). 6443 students were included in this study from six universities from the northern and southern hemispheres. Students in southern hemisphere cities had earlier sleep timings than those in the northern cities. Daily irradiance was higher in the southern hemisphere cities. The amount of time spent outside, age and sex, but not daily irradiance, influenced sleep timings. Study 2 explored the impact of an analogue traumatic event (trauma film) in students who were either sleep deprived or not sleep deprived on intrusive memories ("flashbacks"), sleep physiology and the impact of an increased risk of a mood disorder on this relationship. In this study the sleep deprived participants (n=19) reported fewer intrusive memories to the trauma film than those not sleep deprived (n=22). A change in sleep physiology was observed in the first sleep period following the trauma film, which was more pronounced in the sleep deprived group: increased levels of arousal, REM density and activity in the occipital region. Only three participants at-risk of a mood disorder completed study 2: their data are presented as case studies. In conclusion this research has demonstrated that differences in sleep timings exist between cities in the southern and northern hemispheres and has confirmed that many factors can influence sleep timing. It has also been demonstrated that following a highly emotional event not sleeping may have a beneficial effect, which has implications for the treatment of people after trauma.
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Manganaro, Alessia. "Functional differentiation along the dorso-ventral axis of the hippocampus." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:a7b47ea6-d9f4-4999-a0be-12980ea81d90.
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The hippocampus plays an important role in the processing of spatial memory. During exploration, theta oscillations (4-12 Hz) are prominent in the hippocampus, whereas during sleep and rest irregular sharp wave/ripple (SWR) events occur spontaneously in the hippocampus and may support memory consolidation. To date, the ventral sub-region of the rodents hippocampus, has received less attention relative to the more accessible dorsal part. It has been suggested that spatial information decreases along the septo-temporal axis in favour of coding salient features and coordinated oscillatory activity might enable the binding of spatial and nonspatial information. The first goal of my research was to investigate how the spatial representation by dorsal and ventral neurons is organised by theta oscillations in the hippocampal network. The second goal was to investigate the role of the ventral hippocampus in spatial learning. Finally, the third goal examined to what extent the firing relationships established during spatial learning are replayed during subsequent sleep in the ventral CA1. I recorded the network activity of dorsal and ventral CA1 in rats performing a spatial memory task on the cheese board maze (Dupret et al., 2010). By using parallel multi-channel extracellular recordings in the dorsal and ventral portions of the hippocampus in behaving rats, I found that dorsal and ventral CA1 were theta coupled at particular times of the spatial learning. High coherence periods across the two regions were characterized by a strong speed-modulation of ventral theta oscillations, which was absent in other conditions. During sleep, it was found that SWR-related activity was presented in the ventral hippocampus as well, when the coordinated population activity established in spatial learning was reactivated within the two sub-regions. By contrast, reactivation across the two regions was observed outside the SWRs epochs. Overall, the data suggests that the ventral hippocampus might be involved in the processing of salient features of the environment such as rewards. On a temporal scale, this non-spatial information might be integrated to the spatial information provided by the dorsal hippocampus during theta oscillation. During sleep/rest periods, the coordinated communication of learned information might underlie the consolidation of memory traces.
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Chihabi, Kutibh. "Protein Kinase Mzeta (PKM-ζ) Regulates Kv1.2 Dependent Cerebellar Eyeblink Classical Conditioning." ScholarWorks @ UVM, 2017. http://scholarworks.uvm.edu/graddis/719.
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Learning and memory has been a topic that has captured the attention of the scientific and public communities since the dawn of scientific discovery. Without the faculty of memory, mammals cannot experience nor function in the world; among homosapiens specifically, language, relationships, and personal identity cannot be developed (Eysenck, 2012). After all, some philosophers such as John Locke argued we are nothing but a collection of past memories in which we have developed and improved upon (Nimbalkar, 2011).
Understanding the cellular mechanisms behind learning, and the subsequent formation of memory, has been a topic that has garnered scientific interest for many decades. One particular kinase that has been at the center of attention in the last decade is the serine/threonine kinase PKM-ζ, an N-terminal truncated form of PKC-ζ that renders it constitutively active (Hernandez et al., 2003). PKM-ζ has long been implicated in a cellular correlate of learning, long-term potentiation (LTP). Inhibition of PKM-ζ with Zeta-inhibitory peptide (ZIP) has been shown in many brain structures to disrupt maintenance of AMPA receptors, irreversibly disrupting numerous forms of learning and memory that have been maintained for weeks.
The voltage-gated potassium channel Kv1.2 is a critical modulator of neuronal physiology, including dendritic excitability, action potential propagation, and
neurotransmitter release. While expressed in various mammalian tissues, Kv1.2 is most prevalent in the cerebellum where it modulates both dendritic excitability of Purkinje cells (PCs) and basket cell (BC) inhibitory input to PCs. Because PCs are the main computational unit of the cerebellar cortex and provide its sole output (Napper et al., 1988; Harvey et al., 1991), regulation of synaptic Kv1.2 is predicted to have a major role in cerebellar function. Pharmacological inhibition of Kv1.2 in cerebellar PC dendrites increases excitability (Khavandgar et al., 2005), while its inhibition in BC axon terminals increases inhibition to PCs (Southan & Robertson, 1998). Interestingly, two prior studies have demonstrated that PKC-ζ, an atypical Protein Kinase C, is able to phosphorylate and bind cerebellar Kvβ2, a Kv1.2 auxiliary subunit. (Gong et al., 1999; Croci et al., 2003).
Delay eyeblink conditioning (EBC) is an established model for the assessment of cerebellar learning. Despite being highly expressed in the cerebellum, no studies have examined how regulation of cerebellar PKM-ζ may affect cerebellar-dependent learning and memory nor have they examined the possible effect PKM-ζ may have on Kv1.2. The goal of this dissertation was to determine whether PKM-ζ could modulate EBC in a Kv1.2 dependent manner. Through the use of microscopy techniques we have shown that PKM-ζ is highly expressed in the cerebellar cortex, primarily in the PC, and by the use of pharmacological manipulations, it was found that PKM-ζ has an important role in regulating the acquisition of EBC. Through the use of biotinylation, flow cytometry, and behavioral manipulations, it was determined that PKM-ζ regulates Kv1.2 during eyeblink conditioning. These studies provided the first evidence that PKM-ζ has a role for learning and memory in the cerebellum, and the first evidence of PKM-ζ regulating a voltage-gated ion channel rather than a ligand-gated ion channel such as AMPA receptors.
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Kolmogorova, Daria. "Sex Differences In the Enduring Neuroinflammatory and Behavioural Sequelae of Systemic Immune Challenge During Puberty." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42155.
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Puberty is a critical period for sexual maturation during which the sex-specific reorganization and remodelling of the pubertal brain facilitate sex biases in stress sensitivity. Pubertal (i.e., six-week-old) CD-1 mice treated with the bacterial endotoxin lipopolysaccharide (LPS; 1.5 mg/kg body weight, ip) show several sex-specific changes to the neuroendocrine and behavioural systems of several reproductive and non-reproductive functions. One promising explanation for the elusive mechanisms driving the sex-specific outcomes of pubertal immune challenge may lie in the cascade of neuroimmune events induced by this systemic immune stressor. This doctoral thesis tested the hypothesis that sex-specific responses of the pubertal neuroimmune network contribute to sex differences in the enduring outcomes of pubertal immune challenge on hippocampus-dependent cognitive processes. Male and female CD-1 mice are equally vulnerable to enduring impairments in spatial memory following pubertal LPS exposure. Across brain regions for cognition and stress regulation, pubertal LPS treatment alters baseline sex differences in microglial expression and morphology in a sex-dependent manner. The temporary female-specific increase in whole-brain blood-brain barrier permeability during LPS-induced sickness may have facilitated the apparent female bias in LPS-induced changes to pubertal microglia. In the context of sex- and region-specific residual effects of pubertal LPS-induced sickness on microglial expression and morphology, pubertal LPS treatment may accelerate certain neurodevelopmental processes in males but not females. The innate sex differences in the pubertal neuroimmune network highlighted by these studies underscore how a systemic immune challenge precipitates sex biases in immune-mediated disorders of brain and behaviour during adulthood.
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Hunt, Laurence T. "Modelling human decision under risk and uncertainty." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:244ce799-7397-4698-8dac-c8ca5d0b3e28.
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Humans are unique in their ability to flexibly and rapidly adapt their behaviour and select courses of action that lead to future reward. Several ‘component processes’ must be implemented by the human brain in order to facilitate this behaviour. This thesis examines two such components; (i) the neural substrates supporting action selection during value- guided choice using magnetoencephalography (MEG), and (ii) learning the value of environmental stimuli and other people’s actions using functional magnetic resonance imaging (fMRI). In both situations, it is helpful to formally model the underlying component process, as this generates predictions of trial-to-trial variability in the signal from a brain region involved in its implementation. In the case of value-guided action selection, a biophysically realistic implementation of a drift diffusion model is used. Using this model, it is predicted that there are specific times and frequency bands at which correlates of value are seen. Firstly, there are correlates of the overall value of the two presented options, and secondly the difference in value between the options. Both correlates should be observed in the local field potential, which is closely related to the signal measured using MEG. Importantly, the content of these predictions is quite distinct from the function of the model circuit, which is to transform inputs relating to the value of each option into a categorical decision. In the case of social learning, the same reinforcement learning model is used to track both the value of two stimuli that the subject can choose between, and the advice of a confederate who is playing alongside them. As the confederate advice is actually delivered by a computer, it is possible to keep prediction error and learning rate terms for stimuli and advice orthogonal to one another, and so look for neural correlates of both social and non-social learning in the same fMRI data. Correlates of intentional inference are found in a network of brain regions previously implicated in social cognition, notably the dorsomedial prefrontal cortex, the right temporoparietal junction, and the anterior cingulate gyrus.
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Helene, André Frazão. "Aquisição e uso de memória implícita." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-23082007-152334/.
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A idéia de que memória possa ser segregada em diferentes sistemas e processos possui uma longa história. O desenvolvimento desta concepção esteve associada a casos clínicos envolvendo pacientes amnésicos, estimulando a noção da existência de funções cognitivas específicas relacionadas ao funcionamento de regiões específicas do sistema nervoso. Considerando o contexto histórico no qual se inserem os modelos de memória de longa duração explícita e implícita, a proposta do presente trabalho foi avaliar (1) a extensão da aquisição de conhecimento implícito percepto-motor por meio da imaginação vista aqui como um mecanismo de manipulação de informações na memória operacional, por controle da atenção, e (2) se conhecimento implícito adquirido num dado contexto de treino pode ser utilizado em novos contextos, contrariando conceitos estabelecidos na área, de que esse tipo de conhecimento está firmemente associado ao contexto em que se deu a aquisição. O Experimento 1 mostrou inequivocamente que há aquisição de habilidades motoras por meio de treino imaginativo e, adicionalmente, que essa aquisição segue um curso temporal idêntico àquele observado na aquisição por treino real, sugerindo que ambos os tipos de aquisição exibem propriedades similares, podendo ser equivalentes. O Experimento 2 mostrou que a aquisição de conhecimento implícito envolvendo leitura de texto cujos caracteres foram submetidos a variados tipos de rotação favorece o desempenho na leitura de texto com rotação completamente nova, indicando que o conhecimento implícito adquirido previamente foi flexivelmente empregado no desempenho da nova tarefa. No conjunto, esses resultados mostram que a manipulação de conteúdos na memória operacional permite adquirir conhecimento implícito de-cima-para-baixo e que a utilização desse tipo de conhecimento não está restrita ao contexto de sua aquisição, podendo ser empregado flexivelmente em novas situações. Esses resultados indicam para a necessidade de revisão dos conceitos vigentes sobre a interação entre sistemas de memória e sobre as propriedades do sistema de memória implícitaThe notion that memory may be dissociated in distinct systems is antique. The development of this assumption seems to be associated with studies involving amnesic patients, which contributed for the notion that specific cognitive functions are underlied for specific brain regions. Taking into account the historic context in which the models for explicit and implicit long-term memory developed, the aims of this study was to evaluate (1) to which extent there is acquisition of perceptual-motor implicit knowledge by way of imagery - seen here as a manner of handling information in working memory by control of attention, and (2) to which extent implicit knowledge acquired in a specific context may be used to solve problems in novel contexts, confronting established assumptions that this type of knowledge is strongly associated to the context of its acquisition. The Experiment 1 showed that there is acquisition of perceptual-motor implicit knowledge by way of imagination; the time-course for this acquisition is similar to that seen when acquisition occurs by actual task performance, suggesting that similar properties underlie both types of acquisition. The Experiment 2 showed that prior implicit knowledge acquisition related to reading rotated texts favors performance for reading texts with completely novel types of rotations, indicating the occurrence of transfer of training and, more importantly, that implicit knowledge was flexibly used for performance of a novel task. Taken together, these results show that handling information in working memory promotes top-down acquisition of perceptualmotor implicit knowledge and that this type of knowledge is not strictly associated to the specific context of its acquisition, being used for novel tasks. These results indicate the need for a review of the current assumptions about the interaction of memory systems and about the admitted properties of the implicit memory system.
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Byrom, Nicola. "Towards an understanding of the role of associative learning in risk for mental health problems." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:2d566024-1215-49e3-b1d6-666a8f99838b.
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The ability to prioritize information enables us to think and take action without being overwhelmed by external stimuli or internal thoughts and feelings. Neuroticism is associated with altered processing of emotional information but differences in the processing of emotional information may arise from basic differences in information processing, such as altered processes of attention, changes in sensitivity to salient information, or differences in the ability to encode conjunctions of information. Through this thesis, I explore the relationship between neuroticism and processing of non-emotional information, with a particular focus on learning about combinations of information. Associative learning paradigms were used to test ability to learn about combinations of information and neuroticism was observed to be associated with strong non-linear discrimination learning. The tendency to focus on specific details was associated with weak non-linear discrimination learning. A novel model of associative learning is presented, offering an account for how variation in the ability to engage in non-linear discrimination learning might be understood. Mechanisms underlying the association between neuroticism and strong non-linear discrimination learning were explored. Neuroticism was not found to be associated with a tendency to focus on specific details or shifts in attention towards goal relevant information. Neuroticism was not found to be associated with enhanced ability to identify feature conjunctions, altered sensitivity to the relative validity of stimuli or pre-exposure of stimuli. The importance of understanding individual differences in processes of associative and the value of associative learning tasks to look at information processing biases underlying neuroticism are discussed.
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SKELTON, MATTHEW RYAN. "EFFECTS OF NEONATAL 3,4-METHYLENEDIOXYMETHAMPHETAMINE ON HIPPOCAMPAL GENE EXPRESSION, SPATIAL LEARNING AND LONG-TERM POTENTIATION." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148067008.
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Pützer, Anika [Verfasser], Oliver T. [Gutachter] Wolf, Martin [Gutachter] Brüne, and Urs M. [Gutachter] Nater. "Olfactory cues in associative learning, emotional memory and stress / Anika Pützer ; Gutachter: Oliver T. Wolf, Martin Brüne, Urs M. Nater ; International Graduate School of Neuroscience." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/121786010X/34.
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Steffens, Adriana. "Cortisol Levels and Voltage Conditions of College Students." ScholarWorks, 2015. https://scholarworks.waldenu.edu/dissertations/273.
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There is a limited research base on low voltage brain conditions, which are characterized by electrical activity being measured at below 20 microvolts. The purpose of this study was to examine the relationship between saliva cortisol levels and voltage using an EGG in a college student population. Illuminating this relationship is important to inform how low voltage conditions can affect daily memory and cognitive functioning of undergraduate college students that may be a result of stress. The college student population may be vulnerable to the low voltage condition because of stress from the transition between teenage and adult life and related social and academic pressures. Sapolsky's theory of stress, which hypothesized that high cortisol levels will manifest as a low voltage condition, guided this study. The sample included 60 undergraduate students recruited by flyers distributed on the campus of a liberal arts college. A multiple regression analysis was used to examine the relationship between explain the variables. Although no low voltage was found in this study sample, the study results contribute to positive social change by providing a better understanding for students and staff of brain functioning when exposed to chronic stress and encourage the implementation of programs for managing stress and prevention of stress before it reaches a chronic state and negatively impacts brain functioning.
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Sanku, Rajesh Kishore kumar. "DEVELOPMENT AND BIOLOGICAL EVALUATION OF CARBONIC ANHYDRASE MODULATORS AS POTENTIAL NOOTROPICS AND ANTICANCER AGENTS." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/487142.
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Pharmaceutical SciencesPh.D.
Cancer is the second most common cause of death in the world. One of the objectives of this thesis is to biologically evaluate a series of anti-cancer polymeric aromatic/heterocyclic bis-sulfonamides and pyridinium sulfonamides which were synthesized from three established aminosulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitor pharmacophores. Testing of these novel inhibitors and their precursors against a panel of membrane-bound CA isoforms, including tumor-overexpressed CA IX and XII and cytosolic isozymes, identified nanomolar-potent inhibitors against both classes and several compounds with medium isoform selectivity. In the case of pyridinium sulfonamides we used complexes of the inhibitors with cyclodextrins or sulfocalixarene to enhance aqueous solubility for biological testing. The ability of CA inhibitors to kill tumor cells overexpressing CA IX and XII was tested under normoxic and hypoxic conditions, using 2D and 3D in vitro cellular models. The study identified a nanomolar potent PEGylated bis-sulfonamide CA inhibitor (25), as well as cyclodextrin and sulfocalixarenes complexes, which were able to significantly reduce the viability of colon HT-29, breast MDA-MB231, and ovarian SKOV-3 cancer cell lines, thus revealing the potential of polymer conjugates in CA inhibition and cancer treatment. As a different disease state yet still a concern, cognitive dysfunction markedly impacts patients with a host of psychiatric conditions including attention deficit hyperactivity disorder, autism spectrum disorder, drug addiction, schizophrenia, depression, bipolar disorder, obsessive-compulsive disorder, and of course, Parkinson’s and Alzheimer’s diseases and other types of dementia. Another objective of this thesis was to profile several series of bis-imidazoles for physicochemical, in-vitro and in-vivo properties as potential memory and learning enhancers (nootropics). Biological testing on eight isozymes of carbonic anhydrase (CA) present in the human brain revealed compounds with nanomolar potency against at least one membrane bound, cytosolic or mitochondrial CA isozymes, combined with good physicochemical properties. We also identified lead compounds with the ability to rescue experimental animals from drug-induced memory deficits, using an optimized Novel Object Recognition Task (NORT) procedure.
Temple University--Theses
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Agnes, Everton João. "Estabilidade de atividade basal, recuperação e formação de memórias em redes de neurônios." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/108536.
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O encéfalo, através de complexa atividade elétrica, é capaz de processar diversos tipos de informação, que são reconhecidos, memorizados e recuperados. A base do processamento é dada pela atividade de neurônios, que se comunicam principalmente através de eventos discretos no tempo: os potenciais de ação. Os disparos desses potenciais de ação podem ser observados por técnicas experimentais; por exemplo, é possível medir os instantes dos disparos dos potenciais de ação de centenas de neurônios em camundongos vivos. No entanto, as intensidades das conexões entre esses neurônios não são totalmente acessíveis, o que, além de outros fatores, impossibilita um entendimento mais completo do funcionamento da rede neural. Desse modo, a neurociência computacional tem papel importante para o entendimento dos processos envolvidos no encéfalo, em vários níveis de detalhamento. Dentro da área da neurociência computacional, o presente trabalho aborda a aquisição e recuperação de memórias dadas por padrões espaciais, onde o espaço é definido pelos neurônios da rede simulada. Primeiro utilizamos o conceito da regra de Hebb para construir redes de neurônios com conexões previamente definidas por esses padrões espaciais. Se as memórias são armazenadas nas conexões entre os neurônios, então a inclusão de um período de aprendizado torna necessária a implementação de plasticidade nos pesos sinápticos. As regras de modificação sináptica que permitem memorização (Hebbianas) geralmente causam instabilidades na atividade dos neurônios. Com isso desenvolvemos regras de plasticidade homeostática capazes de estabilizar a atividade basal de redes de neurônios. Finalizamos com o estudo analítico e numérico de regras de plasticidade sináptica que permitam o aprendizado não-supervisionado por elevação da taxa de disparos de potenciais de ação de neurônios. Mostramos que, com uma regra de aprendizado baseada em evidências experimentais, a recuperação de padrões memorizados é possível, com ativação supervisionada ou espontânea.The brain, through complex electrical activity, is able to process different types of information, which are encoded, stored and retrieved. The processing is based on the activity of neurons that communicate primarily by discrete events in time: the action potentials. These action potentials can be observed via experimental techniques; for example, it is possible to measure the moment of action potentials (spikes) of hundreds of neurons in living mice. However, the strength of the connections among these neurons is not fully accessible, which, among other factors, preclude a more complete understanding of the neural network. Thus, computational neuroscience has an important role in understanding the processes involved in the brain, at various levels of detail. Within the field of computational neuroscience, this work presents a study on the acquisition and retrieval of memories given by spatial patterns, where space is defined by the neurons of the simulated network. First we use Hebb’s rule to build up networks of spiking neurons with static connections chosen from these spatial patterns. If memories are stored in the connections between neurons, then synaptic weights should be plastic so that learning is possible. Synaptic plasticity rules that allow memory formation (Hebbian) usually introduce instabilities on the neurons’ activity. Therefore, we developed homeostatic plasticity rules that stabilize baseline activity regimes in neural networks of spiking neurons. This thesis ends with analytical and numerical studies regarding plasticity rules that allow unsupervised learning by increasing the activity of specific neurons. We show that, with a plasticity rule based on experimental evidences, retrieval of learned patterns is possible, either with supervised or spontaneous recalling.
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Takeuchi, Margareth Yuri. "Estudo do uso de mapa conceitual na promoção de aprendizagem significativa de conteúdo de neurociência na graduação." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-08122009-102302/.
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Os estudos dos processos cognitivos propiciam um cenário promissor para a realização de pesquisas visando uma maior compreensão de como o funcionamento do cérebro pode favorecer a educação, possibilitando o desenvolvimento de novas teorias e abordagens que estimulem a aprendizagem. O presente trabalho abordará principalmente como se dá a aquisição, o armazenamento, processamento e a recuperação do conhecimento do ponto de vista da neurociência e de que forma o mapa conceitual (MC) pode mapear o conhecimento do indivíduo. O MC pode ser utilizado tanto como uma estratégia de aprendizagem para a compreensão de conceitos-chave bem como as relações entre estes quanto para promover o pensamento crítico do indivíduo. É uma representação gráfica bidimensional cuja estrutura permite organizar visualmente as relações entre conceitos que podem ser indicadas por palavras, frases e símbolos. É usado para facilitar o aprendizado ao hierarquizar os conceitos por meio de construções significativas para o indivíduo. Os conceitos aparecem nas caixas e as relações nas linhas que os unem: a dois conceitos conectados chamamos de proposição. Durante a construção de um MC o indivíduo exercita a sua capacidade de estabelecer relações entre o conhecimento que já tem e o adquirido no decorrer da aprendizagem ao representar graficamente os conceitos sobre um determinado assunto.The study of cognitive processes provide a promising scenario to research aimed at better understanding of how the functioning of the brain may promote the education, enabling the development of new theories and approaches that encourage learning. This work will mainly occurs as the acquisition, storage, processing and retrieval of knowledge from the viewpoint of neuroscience, and how the conceptual map can map the knowledge of the individual. The conceptual map (CM) can be used both as a strategy of learning for the understanding of key concepts and relations between them and to promote critical thinking of the individual. Two-dimensional graphical representation, the CM allows visually organize the relationships between concepts. This structure from the wider concepts up to less comprehensive and relations between them can be indicated by words, phrases and symbols. It is used to facilitate the learning concepts ranking by building significant to the individual. The concepts appear in the boxes and lines that unite them: two concepts connected call proposition. During the construction of a CM, the individual exercises its ability to establish relationships between knowledge that he has already acquired in the course of learning to represent graphically the concepts of a particular subject.
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Leganes, Fonteneau Mateo. "Attentional, hedonic and interoceptive correlates of implicit processes in addiction : a learning perspective." Thesis, University of Sussex, 2019. http://sro.sussex.ac.uk/id/eprint/81901/.
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Matos, Pinto Thiago. "Computational models of intracellular signalling and synaptic plasticity induction in the cerebellum." Thesis, University of Hertfordshire, 2013. http://hdl.handle.net/2299/11560.
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Many molecules and the complex interactions between them underlie plasticity in the cerebellum. However, the exact relationship between cerebellar plasticity and the different signalling cascades remains unclear. Calcium-calmodulin dependent protein kinase II (CaMKII) regulates many forms of synaptic plasticity, but very little is known about its function during plasticity induction in the cerebellum. The aim of this thesis is to contribute to a better understanding of the molecular mechanisms that regulate the induction of synaptic plasticity in cerebellar Purkinje cells (PCs). The focus of the thesis is to investigate the role of CaMKII isoforms in the bidirectional modulation of plasticity induction at parallel fibre (PF)-PC synapses. For this investigation, computational models that represent the CaMKII activation and the signalling network that mediates plasticity induction at these synapses were constructed. The model of CaMKII activation by calcium-calmodulin developed by Dupont et al (2003) replicates the experiments by De Koninck and Schulman (1998). Both theoretical and experimental studies have argued that the phosphorylation and activation of CaMKII depends on the frequency of calcium oscillations. Using a simplified version of the Dupont model, it was demonstrated that the CaMKII phosphorylation is mostly determined by the average calcium-calmodulin concentration, and therefore depends only indirectly on the actual frequency of calcium oscillations. I have shown that a pulsed application of calcium-calmodulin is, in fact, not required at all. These findings strongly indicate that the activation of CaMKII depends on the average calcium-calmodulin concentration and not on the oscillation frequency per se as asserted in those studies. This thesis also presents the first model of AMPA receptor phosphorylation that simulates the induction of long-term depression (LTD) and potentiation (LTP) at the PF-PC synapse. The results of computer simulations of a simple mathematical model suggest that the balance of CaMKII-mediated phosphorylation and protein phosphatase 2B (PP2B)-mediated dephosphorylation of AMPA receptors determines whether LTD or LTP occurs in cerebellar PCs. This model replicates the experimental observations by Van Woerden et al (2009) that indicate that CaMKII controls the direction of plasticity at PF-PC synapses. My computer simulations support Van Woerden et al’s original suggestion that filamentous actin binding can enable CaMKII to regulate bidirectional plasticity at these synapses. The computational models of intracellular signalling constructed in this thesis advance the understanding of the mechanisms of synaptic plasticity induction in the cerebellum. These simple models are significant tools for future research by the scientific community.
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Narula, Vaibhav, Antonio Giuliano Zippo, Alessandro Muscoloni, Gabriele Eliseo M. Biella, and Carlo Vittorio Cannistraci. "Can local-community-paradigm and epitopological learning enhance our understanding of how local brain connectivity is able to process, learn and memorize chronic pain?" Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-230803.
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The mystery behind the origin of the pain and the difficulty to propose methodologies for its quantitative characterization fascinated philosophers (and then scientists) from the dawn of our modern society. Nowadays, studying patterns of information flow in mesoscale activity of brain networks is a valuable strategy to offer answers in computational neuroscience. In this paper, complex network analysis was performed on the time-varying brain functional connectomes of a rat model of persistent peripheral neuropathic pain, obtained by means of local field potential and spike train analysis. A wide range of topological network measures (14 in total, the code is publicly released at: https://github.com/biomedical-cybernetics/topological_measures_wide_analysis) was employed to quantitatively investigate the rewiring mechanisms of the brain regions responsible for development and upkeep of pain along time, from three hours to 16 days after nerve injury. The time trend (across the days) of each network measure was correlated with a behavioural test for rat pain, and surprisingly we found that the rewiring mechanisms associated with two local topological measure, the local-community-paradigm and the power-lawness, showed very high statistical correlations (higher than 0.9, being the maximum value 1) with the behavioural test. We also disclosed clear functional connectivity patterns that emerged in association with chronic pain in the primary somatosensory cortex (S1) and ventral posterolateral (VPL) nuclei of thalamus. This study represents a pioneering attempt to exploit network science models in order to elucidate the mechanisms of brain region re-wiring and engram formations that are associated with chronic pain in mammalians. We conclude that the local-community-paradigm is a model of complex network organization that triggers a local learning rule, which seems associated to processing, learning and memorization of chronic pain in the brain functional connectivity. This rule is based exclusively on the network topology, hence was named epitopological learning.
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Vandenberghe, Muriel. "Les processus d'apprentissage préservés dans l'amnésie: étude neuropsychologique et cognitive." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210585.
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