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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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Use of dynamic environments in the study of spatial memory
Staňková, Anna ; Svoboda, Jan (advisor) ; Vodička, Martin (referee)
Spatial memory allows movable organisms to orientate and stay therefore alive in an environment. At the beginning of previous century general rules of spatial memory were studied in static experimental conditions. Today's goal is to extend knowledge about its function also in dynamic environment. As a part of declarative memory, spatial memory depends on proper functionality of hippocampus. Hippocampus is considered to be centre of spatial memory not only because of spatial impairment when damaged, but also thanks to presence of place-specific neurons in several areas of hippocampus. In research of spatial memory experimental mazes are used with possibility to manipulate with orientation cues, maze itself and surrounding conditions. It is possible to make one-shot changes or continual changes. It could be rotation of cues and landmarks, transition of maze across the room, rotation of maze etc. Tasks in dynamic environment are more demanding on cognition and so spatial orientation, which makes them more sensitive to damages of spatial memory. This could be the way of using them as a diagnostic method in medicine.
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Hippocampal neuronal representation of a moving object in a novel spatial avoidance task
Ahuja, Nikhil ; Stuchlík, Aleš (advisor) ; Jiruška, Přemysl (referee) ; Telenský, Petr (referee)
In real world environments, animals need to organize their behavior relative to other moving animals or objects; when hunting a predator, when migrating in groups or during various social interactions. In all of these situations, the animal needs to orient relative to another moving animal/object. To understand the role of the hippocampus in this ability we adopted a two-step approach. We developed a task that would mimic important elements of this behavior in the laboratory. The task required the rats to assess not only their distance from the moving object but also their position relative to the object. We further studied how neurons in the hippocampal CA1 subfield encode the subject, the moving object and the environment in the behavioral paradigm and how do these representations interact among themselves. In rats, we aimed to characterize spatial behaviors relative to moving objects and to explore the cognitive mechanisms controlling these behaviors. Three groups of animals were trained to avoid a mild foot-shock delivered in one of three positions: either in front, on the left side, or the right side of a moving robot. Using different variations of the task, we also probed whether avoidance was simply due to increased noise level or size of the retinal image or appearance of the robot. As the...
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Role of hippocampal neurons in creation of cognitive schemas and higher-order spatial relationships
Lebedeva, Maria ; Kelemen, Eduard (advisor) ; Kopřivová, Jana (referee)
The hippocampus is the key structure in formation of representations of space (cognitive maps) in rats. Formation of spatial representations of simple environments has been described in details, in this work we focused on emergence of a spatial map of a complex environment from individual simple maps. A radial-arm maze was used to model a complex environment, where each arm was surrounded by unique pattern of proximal visual landmarks. Long Evans rats were allowed to explore gradually four different arms of the maze in a sequence of three sessions. During the first and second sessions rats separately visited two novel pairs of neighboring arms (arms 1 and 2 in the first session, arms 3 and 4 in the second session). In the third session rats were exposed to a new combination of already familiar arms (arms 2 and 3) to study how the two hippocampal maps, acquired originally as independent of each other, are integrated as the rat learns about their spatial relationship. Rats were exposed to this sequence of three sessions twice - before and after sleep. The activity of hippocampal neurons was recorded using a microelectrode system during the maze exploration and sleep. Our first observations suggest that representation of a complex environment neither is a simple combination of preexisting individual...
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Use of dynamic environments in the study of spatial memory
Staňková, Anna ; Svoboda, Jan (advisor) ; Vodička, Martin (referee)
Spatial memory allows movable organisms to orientate and stay therefore alive in an environment. At the beginning of previous century general rules of spatial memory were studied in static experimental conditions. Today's goal is to extend knowledge about its function also in dynamic environment. As a part of declarative memory, spatial memory depends on proper functionality of hippocampus. Hippocampus is considered to be centre of spatial memory not only because of spatial impairment when damaged, but also thanks to presence of place-specific neurons in several areas of hippocampus. In research of spatial memory experimental mazes are used with possibility to manipulate with orientation cues, maze itself and surrounding conditions. It is possible to make one-shot changes or continual changes. It could be rotation of cues and landmarks, transition of maze across the room, rotation of maze etc. Tasks in dynamic environment are more demanding on cognition and so spatial orientation, which makes them more sensitive to damages of spatial memory. This could be the way of using them as a diagnostic method in medicine.
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