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Hippocampal activity during consolidation of complex spatial representations
Lavrova, Kseniia ; Kelemen, Eduard (advisor) ; Blahna, Karel (referee)
In the real world, we often need to understand complex spatial relationships and integrate existing knowledge. For example, when we learn a new route between familiar places, we need to integrate the new knowledge and create a new cognitive map of the space. Since the hippocampus is a key structure for episodic memory formation and spatial navigation, we examined the activity of hippocampal CA1 neurons when combining simple maps of a complex space. An experiment was designed, consisting of several phases, in each of which the rat was introduced to four different arms of the maze. In the first phase, the rat explored pairs of non-overlapping arms. In the second, it explored a combination of previously known arms, and in the third, all the arms of the labyrinth. During these visits, the rat had to understand the spatial relationships between the different combinations and create a complete map of the space. My results suggest that the rat was unable to understand the relationship between the independent arms before visiting the entire maze. While exploring the entire labyrinth, a completely new map for the maze was created, and there were also changes in the activity of neurons encoding already known combinations of arms. Keywords: hippocampus, sleep, remapping, place cells
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The role of the m6A pathway on electrophysiological correlates of spatial memory in animal model of Alzheimer's disease
Karkušová, Patrícia ; Telenský, Petr (advisor) ; Hromádka, Tomáš (referee)
Memory is one of the vital cognitive functions and can be divided into two categories, short-term memory and long-term memory. Long - term memory is further divided into explicit (declarative) for facts and events and implicit (non-declarative) memory, covering all other types of long-term memory. Alzheimer's disease is well known for a gradual loss of declarative memory and spatial orientation. It is one of the most common causes of dementia and affects tens of millions of people worldwide. The aim of our study was to determine the effect of inhibition of FTO demethylase on neuronal activity in a rat model of Alzheimer's disease (TgF344-AD) and a control strain (F344-CT), and evaluate the stability of spatial maps. We used tetrodes implanted in hippocampal CA1 subregion to record extracellular neuronal activity. Spiking activity was recorded in two spatially different conditions (familiar, unknown) twice, before and after applications of pharmacological inhibitor of FTO demethylase (MO-I-500). We have also evaluated remapping and map stability related to the application of MO-I- 500. We found the average frequency of neuronal firing rate increased in F344-CT rats in both familiar and novel environments after inhibitor administration, whereas increase in TgF344- AD rats was detected only in the novel...
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Hippocampal coding of positions of visual objects and prediction of their future interactions
Dvořáková, Tereza ; Levčík, David (advisor) ; Nekovářová, Tereza (referee)
The hippocampus is a crucial brain structure involved in spatial navigation. It contains populations of spatially sensitive cells as the place cells, head-direction cells, grid cells, border cells, or object-vector cells. These neurons together create a cognitive map of the environment that serves for navigation in space. The role of hippocampal cells in the encoding of positions of other objects has also been suggested. Other studies found so-called time cells in the hippocampus that are active during specific delays in a behavioral task and associated them with place cells. While there are recent studies researching the encoding of accessible objects' positions, the encoding of objects in the inaccessible space has lacked research. The neural representation of dynamic situations (that constitute the majority of real-world encounters) has also been only scarcely researched. We designed a behavioral task to study the learning of static and dynamic spatial visual scenes presented in the inaccessible space and combined it with single-unit electrophysiological recording from the CA1 area of the hippocampus of freely moving rats. Our results show that rats can discriminate both static and dynamic inaccessible spatial stimuli, and that they prefer dynamic over static stimuli. They can also generalize...
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Induction of neurogenesis and gliogenesis after ischemic CNS injury - the role of Wnt signaling pathway
Koleničová, Denisa ; Anděrová, Miroslava (advisor) ; Nerandžič, Vladimír (referee)
This bachelor thesis is focused on ischemic injury of the central nervous system (CNS), one of the most frequent causes of death and disability in the world, and its possible treatment via the induction of neurogenesis. It consists of three different parts. In the first part, main neurogenic regions of the CNS, the subventricular zone and gyrus dentatus (GD) of the hippocampus, are described at the cellular, as well as molecular level. The second part is mainly dedicated to ischemic injury, to the global and focal brain ischemia. A particular chapter of this part describes changes in neurogenesis and gliogenesis after ischemic injury of the brain, changes in the induction of radial glial cells, proliferation and migration of neural progenitor cells and neuroblasts. In this chapter, we also describe the activation of astrocytes, microglia and NG2 glia (also known as polydendrocytes) after ischemic injury of the CNS. The last, third part of the bachelor thesis, is focused on signaling pathways, which significantly influence neurogenesis: Shh (Sonic hedgehog homolog), Notch and Wnt (Wingles/Integrated) signaling pathways. Special attention is devoted to the Wnt signaling pathway, which is an essential part of molecular mechanisms in nerve cells. Keywords: neurogenesis, gliogenesis, hippocampus, gyrus...
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The role of endothelin receptors type A and B in the model of focal cerebral ischemia in immature rats
Vondráková, Kateřina ; Tsenov, Grygoriy (advisor) ; Říčný, Jan (referee)
Hypoxic-ischemic insult is a most common form of perinatal brain damage that threatens a newborn's life and can leads to permanent neurological sequelae. However, detailed aspects of the cerebral ischemia in the immature brain stay unanswered. We decide to use the model of focal cerebral ischemia induced by intrahippocampal endothelin-1 (ET-1) in 12-days-old rats. The knowledge about consequences of ET-1 induced ischemia and the role of endothelin receptors (ETA and ETB) in ischemia-induced consequences in immature brain are poor at present. Agonists and selective antagonists of the ETA and ETB receptors were used to determine the role of these receptors in the development of ischemia, changes in regional blood flow and tissue oxygenation, local changes of biochemical parameters and acute neuronal death. Our results indicates, that activation of the ETA receptors causes a strong decrease of the blood flow, induced related hypoxia and subsequent neuronal degeneration, whereas activation of ETB receptors has likely modulatory role. Moreover, ischemia causes increase of excitatory amino acids concentration, whereas inhibitory amino acid, except taurine, decreased after ischemia. These facts provides new insights in a case of perinatal ischemia. This thesis demonstrates the wide range of different effects of...
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Induction of neurogenesis and gliogenesis after ischemic injury of CNS
Filipová, Marcela ; Anděrová, Miroslava (advisor) ; Moravec, Jan (referee)
Ischemic injury (stroke) is one of the most common causes of death and disability in humans. Discovery of adult neurogenesis and possibilities to induce neurogenesis by cytokines brought new approaches and hopes in treating the ischemic lesion in future. The aim of this thesis is to describe cellular and molecular mechanisms of neurogenesis, mainly those discovered within last ten years. The first part describes generation of new neurons in the brain under physiological conditions, which is localized in the dentate gyrus of the hippocampus and in the subventricular zone of the lateral ventricles (i.e. in principal neurogenic regions). The second part describes animal models used for studying ischemic injury in rodents and moreover, it focuses on patophysiology of ischemic brain injury, which is accompanied by astrocyte and microglia activation. Further, the ischemia-induced neurogenesis is described in these two major neurogenic regions. Also the important role of NG2 glial cells in central nervous system (CNS) regeneration is pointed out. According to recent findings NG2 glia that are present in all regions of CNS might serve as a potential source of cells for directed differentiation into oligodendrocytes, astrocytes and even neurons during CNS repair/regeneration. In the last part of this work,...
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Immediate early genes as a tool for study of spatial orientation and memory
Bláhová, Veronika ; Němec, Pavel (advisor) ; Telenský, Petr (referee)
Properties of the environment, spatial orientation cues and time-shifting movements are essential for cognitive maps. The understanding of how both space and the animal's position within that space are represented in the brain has been significantly advanced by the discoveries of four principal neuronal types: the place cells, the head direction cells, the grid cells and border cells. Their activity being driven by both allothetic (visual and non-visual landmarks), and idiothetic cues (internal movement cues based on proprioceptive and vestibular information). Brain regions containing aforementioned types of neurons constitute complex spatial representation system. Immediate early genes (IEGs) and their products became sophisticated tool for the study of neural substrate of spatial orientation including magnetic orientation. For further research it is unavoidable to uncover the dynamic of processes related to IEGs in order to better understanding the functions of brain centres involved in rodent navigation circuit. This work summarises our knowledge about spatial orientation of the vertebrates aimed at rodents, in context with detection of IEGs expression as activity markers in neural substrate. There are described most common experimental mazes and most frequent detection methods used in connection with...
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Neurogenesis in the adult brain, its regulation and possible functions
Pištíková, Adéla ; Stuchlík, Aleš (advisor) ; Jiruška, Přemysl (referee)
In this thesis I examine neurogenesis in the adult brain. Neurogenesis takes place in two main neurogenic areas. One area is located at the side of the forebrain ventricle and the other in dentate gyrus of the hippocampus. The forebrain ventricle neurogenesis is important for olfactory discrimination and olfactory memory. In the hippocampus, its function is unclear, but there are several hypotheses about its possible significance. We assume it might function in pattern separation and also be involvedin preventing interference between memory traces. The last chapter I dedicate to the positive and negative regulation of neurogenesis. The manipulations enhancing neurogenesis include voluntary physical activity, enriched environment and SSRI antidepressants. The negative impact on neurogenesis is exerted among other factors by stress, irradiation and a cytostatic Temodal, which is used methodologiclly to block neurogenesis.
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The effect of structural changes in perineuronal nets and deep cooling on synaptic plasticity and memory of tauopathy mice
Šafránková, Kristýna ; Růžička, Jiří (advisor) ; Telenský, Petr (referee)
Tauopathy is accompanied by both loss of neurons and synapses. The neuronal loss is irreversible with very low chance of functional replacement therapy. However, lost synapses could be restored with proper stimuli. Perineuronal nets (PNNs) are serving as a protecting barrier for neurons, on the other hand they are significantly decreasing the synaptic plasticity. Temporary disintegration of the PNNs by enzymatic therapy might lead to rewiring and accelerate processes of memory and learning. Model of Cold Induced plasticity leads to the withdrawal of significant number of synapses across the brain. The recovery of these could be followed in healthy and diseased animals. Moreover, it can stimulate Cold shock protein dependent neuroprotective mechanisms. This master thesis is focused on these two forms of synaptic plasticity models; forced remodeling of PNNs and model of cold induced synaptic plasticity. Both will serve as a tool to modulate processes of memory and learning in the P301S tauopathy, in mice. In detail, the work will follow changes in the number of synapses at the region of CA1 of hippocampus and synaptic protein levels at level of whole hippocampus and behavioral recovery of pre-trained long-term memory task dependent on dorsal hippocampus. Key words: Perineuronal nets, aggrecan,...
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