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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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Non-pharmacological methods for influencing memory consolidation during sleep
Němcová, Monika ; Kopřivová, Jana (advisor) ; Honc, Ondřej (referee)
Sleep plays vital role in many physiological processes of the human body, including the consolidation of memory. The beneficial effects of sleep on memory consolidation have long been known, but only in the last two decades the knowledge of the relationship between sleep and memory has been used to develop interventions to improve memory consolidation during sleep. Two of these approaches are the focus of this work: closed-loop auditory stimulation (CLAS) and targeted memory reactivation (TMR). They are of particular clinical interest, as they are non- pharmacological, which minimizes the risk of dependence and abuse. In addition, they do not impose exogenous force fields on the brain and are, therefore, considered safer than other similar interventions. The aim of this work is to describe CLAS and TMR in detail, to investigate which factors influence their efficacy, and to discuss their clinical potential in the treatment of memory- related disorders.
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Factors affecting long-term memory of aposematic signals in avian predators
Skoumalová, Žaneta ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
The ability to memorize and recognize edible prey from inedible prey is essential for an individuals survival. Many species use aposematic signals for their defense. These are most often represented by distinctive colors or contrast patterns. The aim of this study was to find out in which time the memory consolidation for aposematic pray is achieved and if color or pattern increase its memorability. The choosen model species was the Great tit (Parus major). The comparision was done between handreared naïve birds and wild-caught adults of different age and sex. During the discriminatory task of consolidation experiment, birds were simultaneously presented with palatable and unpalatable prey in the form of paper dummies of bugs, differing in color (red versus green). The birds were divided into three groups with a different interval (0, 1 or 3 hours) for consolidation. The results of consolidation test show that adult birds were more successfull in solving the task than juvenile birds. The only difference between the experimental groups was that the group with one-hour interval achieved better results than other groups. The effect of color of palatable and unpalatable prey on discrimination learning was also found only in adults. Memorability of warning signals was tested using paper bugs of...
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The effect of psilocybin on memory consolidation in rats
Chona, Kembe ; Olejníková, Lucie (advisor) ; Petrásek, Tomáš (referee)
Psychedelics are currently being researched due to their long-lasting antidepressant, anxiolytic and neuroplasticity inducing actions. The mechanism by which they induce these effects remains poorly understood. Here, we decided to investigate a relatively unexplored possibility. A potential interaction of psilocybin administration and sleep and their combined effects on memory consolidation. Memory formation in animals and humans is greatly influenced by sleep manipulation which led us to assess the possibility with spatial memory tasks. We hypothesized that acute psilocybin administration after learning may have a beneficial influence on memory consolidation in rats. To determine whether an interaction with sleep exists we also subjected the rats to combinations of psilocybin and control vehicle with normal sleep and sleep deprivation. Our data did not suggest such an interaction exists. Secondly, we tried to find out if psilocybin and sleep manipulation leads to changes in neuroplasticity-related events. A process that could very likely be the basis of such a proposed beneficial effect. For this purpose, we analysed the expression of the immediate-early gene Arc and the immature neuron marker doublecortin in the rat hippocampus. Doublecortin's expression was not influenced by any of the factors....
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Memory consolidation of mental schemas during sleep
Hanzlík, Adam-František ; Kelemen, Eduard (advisor) ; Janíková, Martina (referee)
A core feature of the human mind is the ability of abstraction. Relying on this ability, a mental or cognitive schema is a memory framework which underlies alike memory representations. In order for newly acquired memory representations to be preserved for long-term storage, they have to undergo memory consolidation and sleep is a major factor in this process. In a rat model, learning in the context of an existing schema is faster and it is characterised by IEG up-regulation. It is presumable that consolidation during sleep enables the extraction of commonalities from alike memory representations, resulting in schema formation. On a mechanistic level, schemata might be formed by a process which (a) employs synaptic potentiation induced by neuronal replay, (b) requires synaptic downscaling and (c) affects overlapping memory representations. This overlapping character of schema creation might be reflected by the nature of neuronal replay in the hippocampus. It appears that individual sleep stages influence schemata consolidation differently. In human experiments on schemata consolidation, the amount of knowledge a participant is given prior to training is critical.
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Role of sleep and elevated introhippocampal corticosterone level in consolidation of traumatic memory in rodents
Brukhnová, Alena ; Kelemen, Eduard (advisor) ; Kopřivová, Jana (referee)
Any disruption of homeostasis causes a stress response that serves to restore balance in the body. Stress hormone levels, such as glucocorticoids, strongly influence the consolidation of episodic memory dependent on the hippocampus. Sleep has beneficial effects on individual types of memory and is necessary for the proper course of consolidation of newly acquired information. Little is known, however, about neuronal processes of memory consolidation for a traumatic event. The topic of this work is to study the combination of these two factors and to determine the effect of elevated levels of corticosterone and sleep on the consolidation of traumatic memory in rats. The theoretical part of this work summarizes the knowledge about memory, sleep and stress. The practical part deals with the experimental procedure combining behavioral (fear conditioning), electrophysiological methods (EEG recording and determination of sleep stages) and pharmacological manipulation (intrahippocampal administration of corticosterone). In summary, we found the effect of high levels of corticosterone in the hippocampus on contextual memory consolidation and on the amount of slow wave sleep. These results can bring new features in the field of traumatic memory consolidation and associated post-traumatic stress disorder....
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Neuronal mechanisms of consolidation of memories for behavioral episodes in sleep
Petránová, Erika ; Kelemen, Eduard (advisor) ; Telenský, Petr (referee)
Memory is an important ability of an individual allowing efficient operations with information acquired during lifetime. Memory is a dynamic process consisting of different phases such as encoding, consolidation and repeated retrieval of the memory. Received information from surrounding environment travels to the short-term storage, from which, in certain amount of time after re-evaluation of its relevance, it is decided about its transport to structures designated for long-term storing. The mechanism used for this transformation is referred to as consolidation. Consolidation occurs on systematic and synaptic level. Positive strengthening effect on memories coded right before sleep has been observed many years ago. The role of sleep in the consolidation of memory representation is still unknown, though there are multiple hypotheses that stress different points of view on the consolidation process. In the last few decades sleep has been given an active role in this process. An interesting problem regarding sleep consolidation is not only the mechanism, but also the preference of a specific type of memory that is being consolidated during sleep. During examination of consolidation of declarative memory, we can observe, in case of episodic memory, an improvement of mainly space-time association...
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Factors affecting long-term memory of aposematic signals in avian predators
Skoumalová, Žaneta ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
The ability to memorize and recognize edible prey from inedible prey is essential for an individuals survival. Many species use aposematic signals for their defense. These are most often represented by distinctive colors or contrast patterns. The aim of this study was to find out in which time the memory consolidation for aposematic pray is achieved and if color or pattern increase its memorability. The choosen model species was the Great tit (Parus major). The comparision was done between handreared naïve birds and wild-caught adults of different age and sex. During the discriminatory task of consolidation experiment, birds were simultaneously presented with palatable and unpalatable prey in the form of paper dummies of bugs, differing in color (red versus green). The birds were divided into three groups with a different interval (0, 1 or 3 hours) for consolidation. The results of consolidation test show that adult birds were more successfull in solving the task than juvenile birds. The only difference between the experimental groups was that the group with one-hour interval achieved better results than other groups. The effect of color of palatable and unpalatable prey on discrimination learning was also found only in adults. Memorability of warning signals was tested using paper bugs of...
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