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Segmentation of amyloid plaques in brains of trangenic rats based on microCT image data
Kačníková, Diana ; Kolář, Radim (referee) ; Chmelík, Jiří (advisor)
The presence of amyloid plaques in the hippocampus highlights the incidence of Alzheimer’s disease. Manual segmentation of amyloid plaques is very time consuming and increases the time that can be used to monitor the distribution of amyloid plaques. Distribution carries significant information about disease progression and the impact of potential therapy. The automatic or semi-automatic segmentation method can lead to significant savings in the time which are required when the disease has rapid progression. The description of amyloid plaques and the computed tomography are included in this work. In this diploma thesis are three implemented algorithms, two of them are based on published articles and one’s own methodological solution. The conclusion of the thesis is a quantitative evaluation of the accuracy of implemented segmentation procedures.
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Analysis of volumetric change of Hippocampus caused by Alzheimer's disease
Pham, Minh Tuan ; Harabiš, Vratislav (referee) ; Walek, Petr (advisor)
Interest in hippocampus increased sharply after his significance in the process of learning and retention of information was published. In particular, considerable interest was in its volume changes and their effect on Alzheimer’s disease. Understanding the structure and function hippocampus would contribute to a more accurate diagnosis of this disease. In this work was created a method of hippocampal segmentation using active contours. With its help, the data composed of both healthy and a diseased patients was segmented and the results were then statistically analyzed using statistical methods such as Kruskal-Walis test, Mann-Whitney test. The level of significance given by results of analysis supports alternative hypothesis that attaches significance of the difference in volume of the hippocampus between studied groups.
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One-trial association task as a basic biological model of episodic memory in rats
Radostová, Dominika ; Stuchlík, Aleš (advisor) ; Horáček, Jiří (referee) ; Telenský, Petr (referee)
One-trial association task as a basic biological model of episodic memory in rats Abstract A very important structure in the animal and human brain is the hippocampus. The study one of its many functions, episodic memory, is facing with the limited possibilities of non-invasive methods. In this regard, animal models are helpful. In order to study the individual components of such a complex ability in detail, a new behavioral task testing the association of temporally close but separate stimuli was developed. The test animals were exposed to a sequence of a sound conditioned stimulus and an unconditioned electric shock, between which there was a delay of 2 seconds. 59% of the rats successfully learned the association as well as the correct escape reaction to solve the task. Based on the results, the so-called One-Trial Trace Escape Reaction task could be a very valuable tool for a more detailed understanding of animals' incidental one-trial learning important for episodic memory. Another important phenomenon investigated in this work is the development of new neurons in the hippocampus in adulthood and its influence on learning and flexibility. After blocking the animals' neurogenesis with the temozolomide, the animals' ability to learn to avoid an invisible sector in the active avoidance task was tested....
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Hippocampus and consolidation of contextual memory in physiological and pathological conditions
Taskina, Sofia ; Kelemen, Eduard (advisor) ; Vlček, Kamil (referee)
afa Contextual memory and context processing are important brain abilities for learning, adap- tation, and overall life. This work aims to understand what these abilities are, what structures and processes support them, and the pathologies associated with them. Such an approach will allow evaluating the significance of contextual memory, understanding how it arises, changes, is retrieved, and forgotten, and also identifying to what extent further discoveries in this field will contribute to the development of treatments for disorders in which contextual processing has undergone alterations. afa Key words: contextual memory, contextual processing, hippocampus, memory consolida- tion, PTSD
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Ontogeny of neural mechanisms of episodic memory
Šafová, Lucie ; Nekovářová, Tereza (advisor) ; Blahna, Karel (referee)
Two brain structures in particular - the hippocampus and the prefrontal cortex (PFC) - are essential for episodic memory, the ability to recall personal experiences with details of time, place, and event. It is their developmental changes that contribute significantly to the progressive development of episodic memory. The hippocampus is a complex structure composed of several subregions that is crucial to the function of the neural basis of episodic memory. Findings show that both neuronal changes within the hippocampus and changes in its volume and the volume of hippocampal subfields influence episodic memory. As in the hippocampus, changes in the prefrontal cortex also affect episodic memory, with the PFC being among the last regions to fully mature and affecting the accuracy of recalling contextual details of episodic memories. The transfer of information between brain regions is also crucial for episodic memories, and is provided by white matter connections (fornix, cingulum, uncinate fasciculus). This thesis summarizes the knowledge about the structures and mechanisms involved in the development of episodic memory and mentions the factors that influence its development. Keywords: episodic memory, ontogeny, hippocampus, prefrontal cortex, synaptic plasticity
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Altered morphology of white and grey matter in patients with Alzheimer disease and Schizophrenia on MRI
Lahutsina, Anastasiya ; Zach, Petr (advisor) ; Horáček, Jiří (referee) ; Němcová, Veronika (referee)
Cortical folding of the anterior cingulate cortex (ACC), particularly the cingulate (CS) and the paracingulate (PCS) sulci, represents a neurodevelopmental marker. Deviations in in utero development in schizophrenia can be traced using CS and PCS morphometry. In the present study, we measured the length of CS, PCS, and their segments on T1 MRI scans in 93 patients with first episode schizophrenia and 42 healthy controls. Besides the length, the frequency and the left-right asymmetry of CS/PCS were compared in patients and controls. Distribution of the CS and PCS morphotypes in patients was different from controls. Parcellated sulcal pattern CS3a in the left hemisphere was longer in patients (53.8 ± 25.7 mm vs. 32.7 ± 19.4 mm in controls, p < 0.05), while in CS3c it was reversed-longer in controls (52.5 ± 22.5 mm as opposed to 36.2 ± 12.9 mm, n.s. in patients). Non parcellated PCS in the right hemisphere were longer in patients compared to controls (19.4 ± 10.2 mm vs. 12.1 ± 12.4 mm, p < 0.001). Therefore, concurrent presence of PCS1 and CS1 in the left hemisphere and to some extent in the right hemisphere may be suggestive of a higher probability of schizophrenia. Measurement of an hippocampal area or volume is useful in clinical practice as a supportive aid for diagnosis of Alzheimer's disease....
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Synchronization of circadian clock in hippocampus
Kubátová, Eliška ; Sumová, Alena (advisor) ; Liška, Karolína (referee)
Circadian rhythms refer to the physiological, biochemical and behavioral changes of the organism with a period of about 24 hours, such as the cycle of sleep and wakefulness, the release of hormones, enzymatic activity or gene expression. Apart from the central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, we find many other peripheral oscillators in which we observe the rhythmic expression of clock genes. In this study, we focused on one of the peripheral brain oscillators located in the hippocampus. The hippocampus is best known for its role in memory formation through the mechanism of long- term potentiation (LTP). The formation of LTP is another process that exhibits circadian variation. Although the rhythmic expression of genes in the hippocampus has already been demonstrated, the mechanisms of synchronization of these clocks remain a subject of investigation. In this study, we studied the effect of candidate substances - N-methyl-D- aspartate (NMDA) and leptin on the circadian clock of the hippocampus. Genetically modified mPer2Luc mice were used as a model. The main goal of the work was to introduce a method of preparing organotypic explants of the hippocampus of these mice for monitoring the circadian clock in real time using the LumiCycle device. Next goal was...
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Consequences of perinatal insult on brain excitability in immature and adult rats
Fábera, Petr ; Mareš, Pavel (advisor) ; Pokorný, Jaroslav (referee) ; Ošlejšková, Hana (referee)
Perinatal insult may lead to a permanent impairment of brain function resulting in the development of epilepsy. Status epilepticus (SE) in immature rats leads to hippocampal hyperexcitability. The functional and morphological changes of the hippocampus are similar to those seen in human temporal lobe epilepsy. The excitability may be influenced by adenosine. Adenosine acts its anticonvulsant effect by activation of A1 receptors (A1R). The concentration of adenosine is regulated by adenosine kinase (ADK) present in two isoforms - ADK-L and -S. The main goal of the thesis is to elucidate the changes in A1R and ADK isoforms expression during intact brain development and after SE. A1R agonist 2-chloro-N6- cyclopentyladenosine (CCPA), as well as inhibition of ADK by 5-iodotubercidin (5-ITU), may bolster the anticonvulsant effect, but their action may correspond with the level of A1R and ADK. Hippocampal excitability in immature rats after LiCl-pilocarpine SE was studied by the model of hippocampal afterdischarges (ADs) and correlated with changes of A1R and ADK in the hippocampus. ADs demonstrated significantly decreased hippocampal excitability shortly after SE induction, whereas significant hyperexcitability accompanied by spontaneous seizures in older rats was shown. Increasing ADK-S expression...
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Early stages of neurodegenerative diseases and their diagnosis using experimental cognitive tests with a specific focus on spatial cognition
Laczó, Martina ; Laczó, Jan (advisor) ; Telenský, Petr (referee) ; Hocko Fajnerová, Iveta (referee)
Early stages of neurodegenerative diseases and their diagnosis using experimental cognitive tests with a specific focus on spatial navigation Abstract This dissertation thesis is focused on early and differential diagnosis of Alzheimer's disease (AD) using experimental cognitive tests. AD starts as a preclinical stage, progresses to the mild cognitive impairment (MCI) and eventually to the dementia stage. It is crucial to diagnose AD very early to slow down its progression. However, the use of specific AD biomarkers, such as amyloid and tau positron emission tomography and cerebrospinal fluid (CSF) biomarkers, is very limited. Experimental spatial navigation and spatial pattern separation tests, unlike conventional cognitive tests, may have a strong diagnostic potential as they depend on brain regions affected early in AD. The first study in a virtual environment showed preference for word-centered navigation in cognitively normal older adults, while participants with early AD preferred body- centered strategy to compensate for neurodegeneration. Using a virtual navigation test, the second study showed different profiles of navigation impairment in MCI participants with AD and other (i.e., non-AD) etiologies and demonstrated that navigation assessment differentiated AD from non-AD participants. Various...
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Advanced neuroimaging methods and their use in evaluation of structural changes of the brain and their cognitive correlates in early diagnosis of neurodegenerative disorders
Lerch, Ondřej ; Hort, Jakub (advisor) ; Rusina, Robert (referee) ; Dušek, Petr (referee)
Advanced neuroimaging methods and their use in evaluation of structural changes of the brain and their cognitive correlates in early diagnosis of neurodegenerative disorders Abstract Neurodegenerative diseases are a heterogeneous group of diseases characterized by the loss of specific neuronal populations caused by the deposition of pathologically altered proteins into the brain tissue. The structural corelate of these pathological changes is a brain atrophy. The most common neurodegenerative disease is Alzheimer's disease (AN). The cholinergic deficit, caused by atrophy of the basal telencephalon (BF), and atrophy of the medial temporal lobe (MTL) are among the hallmarks of AN. Recent advances in imaging methods and image processing techniques have made it possible to measure atrophy at the level of substructures. The aim of this dissertation was to evaluate the potential utility of imaging methods in the assessment of structural changes and their cognitive correlates in the early diagnosis of neurodegeneration, in particular to evaluate the utility of segmentation of the BF nuclei and MTL substructures in the early and differential diagnosis of AN, their mutual relationships and cognitive correlates. We confirmed that differences in atrophy of individual BF and MTL substructures may be utilized in the...
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