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Effect of Sepsis on Dynamics of Hippocampal Oscillations and CA1 Cells
Annu, Kala ; Ježek, Karel (advisor) ; Klement, Daniel (referee) ; Levčík, David (referee)
(CZECH) Sepsí asociovaná encefalopatie (SAE) je závažnou komplikací sepse, která vede k vysoké mortalitě a dlouhodobé mozkové dysfunkci. SAE se často projevuje jako změna vědomí, delirium, kóma, nepozornost a kognitivní poruchy. Poruchy spánku zobrazené jako fragmentace spánku a bdění vyskytující se v akutní fázi sepse byly přímo spojeny se špatnými výsledky u pacientů se sepsí. U osob, které přežily septický šok, se typicky rozvíjí postseptický syndrom charakterizovaný extrémní únavou, poruchami spánku a kognitivními poruchami. Centrální nervový systém, konkrétně hipokampus, je jednou z prvních oblastí, které jsou v důsledku SAE postiženy. Navzdory úloze spánku při udržování funkčního imunitního systému a jeho významu pro konsolidaci paměti zůstává důkladné pochopení vzorců spánku a bdění nedostatečně prozkoumáno. V této práci jsme se zaměřili na pochopení jemné dynamiky oscilací hipokampu na modelu sepse s LPS (10 mg/kg) v uretanové anestezii. Uretan má minimální účinky na dýchací a kardiovaskulární systém, což z něj činí vhodný systém pro studium jemné kinetiky mozkových oscilací bez vnějších senzorických modalit. Dále jsme se zaměřili na potvrzení našich zjištění o architektuře spánku a spektrálních vlastnostech u neanestetizovaných zvířat pod standardizovanou dávkou 5 mg/kg LPS. Dále jsme se...
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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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The effect of latent toxoplasmosis on memory performance in infected persons
Hejduk, Tomáš ; Flegr, Jaroslav (advisor) ; Levčík, David (referee)
The relationship between latent toxoplasmosis and the memory processes has not been studied in detail. There is an assumption of a possible link between latent toxoplasmosis and memory, due to the generally weaker cognitive performance and worse prognosis of Toxoplasma-positive patients with schizophrenia. The aim of this study was to verify whether the latent toxoplasmosis along with Rh phenotype affects the memory of Toxoplasma-infected individuals. Visual-spatial working memory was tested by the Spatial Span test, Meili test and Virtual Four Goals Navigation task. These tests were performed on a group of 307 students of the Faculty of Science, Charles University. The results of these tests demonstrated the negative impact of latent toxoplasmosis on visual-spatial working memory. It was detected that Toxoplasma-positive men remember more subjects with aggressive themes, while Toxoplasma-positive women remember less subjects with aggressive themes. The findings could be related to the previously observed changes in the concentration of testosterone in infected men and women. The protective effect of Rh positivity was not confirmed, as in many sub-tests the worse memory performance was by Rh positive individuals with latent toxoplasmosis. Keywords: Latent toxoplasmosis, Rh factor, visual-spatial...
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Studying the role of striatal cholinergic signaling in control of behaviour and behavioural flexibility
Tyshkevich, Alexandra ; Janíčková, Helena (advisor) ; Levčík, David (referee)
Cognitive flexibility is an important mechanism enabling organisms to adapt to their changing environment. Different brain structures are involved in this complex process. It has been repeatedly shown that the striatum is one of the key structures controlling cognitive flexibility. Striatum receives rich input from different brain regions while its output is rather uniform. Striatal functions and signalling are greatly modulated by dopamine and acetylcholine. A number of studies have shown involvement of striatal acetylcholine and its receptors in the control of cognitive flexibility but very little is known about the role of M4 muscarinic acetylcholine receptors. These receptors are inhibitory, and they have been shown to induce long-term depression in striatal medium spiny neurons, therefore opposing the action of the dopamine D1 receptors. We hypothesize that the inhibitory effect of M4 muscarinic acetylcholine receptors may supress spiny projection neurons coding for outdated and no longer effective behavioural strategy and thus they may be necessary for the flexible change of behaviour. In the present thesis, I investigated the effects of pharmacological antagonism of M4 receptors on cognitive flexibility of mice tested in a simple reversal learning paradigm. Key words: striatum; cholinergic...
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Spatial cognition in rats: processing of information about the position of distant object
Levčík, David
Spatial behavior is widely studied to understand cognition and its neurophysiological substrate. Hippocampus plays a crucial role in many spatial tasks. It is unclear whether hippocampus is necessary for recognizing position of distant objects located in inaccessible space. To address this question we developed a novel operant-conditioning task in which rats recognize position of an object located in an inaccessible space. We assessed the role of the dorsal hippocampus in the task by blocking its activity with muscimol. Our results showed that intact rats use the dorsal hippocampus for recognizing position of the distant object located in the inaccessible part of the environment. In addition, we showed that the cognitive performance in the task is not affected by the changes in motor activity induced by prazosin. Key words: spatial cognition, operant conditioning, hippocampus, muscimol, prazosin
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Spatial cognition in rats: processing of information about the position of distant object
Levčík, David
Spatial behavior is widely studied to understand cognition and its neurophysiological substrate. Hippocampus plays a crucial role in many spatial tasks. It is unclear whether hippocampus is necessary for recognizing position of distant objects located in inaccessible space. To address this question we developed a novel operant-conditioning task in which rats recognize position of an object located in an inaccessible space. We assessed the role of the dorsal hippocampus in the task by blocking its activity with muscimol. Our results showed that intact rats use the dorsal hippocampus for recognizing position of the distant object located in the inaccessible part of the environment. In addition, we showed that the cognitive performance in the task is not affected by the changes in motor activity induced by prazosin. Key words: spatial cognition, operant conditioning, hippocampus, muscimol, prazosin
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Spatial cognition in rats: processing of information about the position of distant object
Levčík, David ; Klement, Daniel (advisor) ; Syka, Josef (referee) ; Hort, Jakub (referee)
Spatial behavior is widely studied to understand cognition and its neurophysiological substrate. Hippocampus plays a crucial role in many spatial tasks. It is unclear whether hippocampus is necessary for recognizing position of distant objects located in inaccessible space. To address this question we developed a novel operant-conditioning task in which rats recognize position of an object located in an inaccessible space. We assessed the role of the dorsal hippocampus in the task by blocking its activity with muscimol. Our results showed that intact rats use the dorsal hippocampus for recognizing position of the distant object located in the inaccessible part of the environment. In addition, we showed that the cognitive performance in the task is not affected by the changes in motor activity induced by prazosin. Key words: spatial cognition, operant conditioning, hippocampus, muscimol, prazosin
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The effect of latent toxoplasmosis on memory performance in infected persons
Hejduk, Tomáš ; Flegr, Jaroslav (advisor) ; Levčík, David (referee)
The relationship between latent toxoplasmosis and the memory processes has not been studied in detail. There is an assumption of a possible link between latent toxoplasmosis and memory, due to the generally weaker cognitive performance and worse prognosis of Toxoplasma-positive patients with schizophrenia. The aim of this study was to verify whether the latent toxoplasmosis along with Rh phenotype affects the memory of Toxoplasma-infected individuals. Visual-spatial working memory was tested by the Spatial Span test, Meili test and Virtual Four Goals Navigation task. These tests were performed on a group of 307 students of the Faculty of Science, Charles University. The results of these tests demonstrated the negative impact of latent toxoplasmosis on visual-spatial working memory. It was detected that Toxoplasma-positive men remember more subjects with aggressive themes, while Toxoplasma-positive women remember less subjects with aggressive themes. The findings could be related to the previously observed changes in the concentration of testosterone in infected men and women. The protective effect of Rh positivity was not confirmed, as in many sub-tests the worse memory performance was by Rh positive individuals with latent toxoplasmosis. Keywords: Latent toxoplasmosis, Rh factor, visual-spatial...
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