|
|
Effects of memantine and riluzole on learning deficits in an animal model of obsessive-compulsive disorder induced by 8-OH-DPAT sensitization
Mainerová, Karolína ; Stuchlík, Aleš (advisor) ; Kelemen, Eduard (referee)
Obsessive-compulsive disorder is a chronic psychiatric disease. It seriously limits the quality of life of patients. Treatment of OCD is not yet fully successful and still many patients are left with debilitating symptoms without functioning medication. Animal models of genetic, behavioral, pharmacological, and optogenetic origins are beneficial in the achievement of new understandings of the disease. Chronic sensitization of serotonin 1A and 7-receptors with an agonist 8-OH-DPAT ((8- hydroxy-2-(di-propylamino)-tetralin hydrobromide) induces perseverative and compulsive behaviors, which is considered to constitute an animal model of OCD. In this thesis, the 8-OH- DPAT model has been tested in the active place avoidance task on Carousel maze to provide information about the model on learning. Second, this model is used to determine, whether co- administration of memantine or riluzole alleviates the cognitive and learning deficits of this model. To uncover these effects, an active place avoidance task on a Carousel maze was used. Measured criteria were total distance, entrances to the shock sector, total number of shocks, and median speed after the shock. During habituation, the animals were sensitized to 8-OH-DPAT (with a control group that did not receive 8-OH-DPAT but only saline). In an...
|
|
|
Hippocampus Dysfunction in Quinpirole Sensitization Model of Obsessive-Compulsive Disorder
Brožka, Hana ; Stuchlík, Aleš (advisor) ; Jendelová, Pavla (referee) ; Kelemen, Eduard (referee)
Obsessive-compulsive disorder (OCD) is a serious psychiatric condition manifested by repeated thoughts followed by stereotypic compulsive behavior. Alterations to cortico-thalamo-striato- cortical circuits are most often implicated in the pathophysiology of OCD. However, many studies have also found a changed volume, shape and activity of the hippocampus in OCD patients. This work focused on the activity of hippocampal CA1 cells during stereotypical checking behavior and on cognitive flexibility in a quinpirole (QNP) sensitization model of OCD. The activity of CA1 hippocampal cells during stereotypical checking was assessed in an enriched open-field test in QNP sensitized rats. Arc+ (activity-regulated cytoskeletal associated protein, or Arg 3.1) mRNA expression profiles were determined in CA1 coronal hippocampal sections following stereotypical checking. After the establishment of stereotypical checking (10 sessions), rats were exposed to the arena and sacrificed after 5 minutes. QNP sensitized animals visited the same objects with the same frequency as during previous sessions, while control rats did not. Locomotor activity was comparable between QNP treated rats and controls. Following sacrifice, rat brains were flash frozen and sliced to 20 µm thick sections. Sections, mounted on slides, were hybridized...
|
|
|
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...
|
|
|
Acoustic stimulation of Slow wave sleep and its influence on consolidation of declarative memory in insomnia
Orendáčová, Mária ; Kopřivová, Jana (advisor) ; Kelemen, Eduard (referee)
Slow-wave sleep plays an important role in consolidation of declarative memory. From electrophysiological point of view, this process is dependent on a common occurrence and mutual integration of neocortical slow oscillations (< 1 Hz), hippocampal sharp-wave ripples (150-250 Hz) and thalamo-cortical sleep spindles (10-15 Hz). Previous studies demonstrated that periodic acoustic stimulation by pink noise pulses applied at frequency of sleep slow oscillation during slow wave sleep leads to prolongation of slow wave sleep and to enhancement in declarative memory performance in normal sleepers. Our study investigated this kind of periodic acoustic stimulation in its relation to sleep architecture and declarative memory of people suffering from insomnia due to which there often comes to a reduction in slow wave sleep which positively correlates with worsening of declarative memory performance. Our aim was to investigate if this kind of comparatively non-invasive brain stimulation has a potential to increase a total length of slow wave sleep and enhance declarative memory performance in insomnia. Our study revealed acoustic stimulation neither improved declarative memory performance nor it increased total length of slow-wave sleep. No positive association was found between level of declarative memory...
|
|
|
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.
|
|
|
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....
|
|
|
EEG correlates of neurodegenerative disorders
Schlezingerová, Nicol ; Telenský, Petr (advisor) ; Kelemen, Eduard (referee)
Due to the aging of the population, there is an increasing incidence of neurodegenerative diseases. In clinical practice there is a need to for a cheap and noninvasive method for screening and early diagnosis of neurodegenerative disorders. To this end, markers of disease progression and prognosis must be determined. EEG correlates provide information that can be used in the diagnosis and prognosis of neurodegenerative disorders. Individual diseases have their specific EEG abnormalities that are closely related to different stages of the disease. Individual illnesses - Alzheimer's disease, Parkinson's disease, Huntington's disease have their specific changes in the basic rhythms of the brain that correlate with motor and cognitive changes. This work focuses on the quantitative (qEEG) correlates of the above-mentioned diseases. Key words: brain, neural activity, EEG, quantitative EEG analysis, biomarker, connectivity, neurodegeneration, Alzheimer's disease, Parkinson's disease, Huntington's disease.
|
|
|
The role of inhibitory interneurons in encoding of complex sounds by the auditory cortex of mouse
Tomáška, Filip ; Tureček, Rostislav (advisor) ; Kelemen, Eduard (referee)
Recent findings suggest, that perception of acoustic stimuli in the mouse auditory cortex relies on categorization of object-based representations. Local neuronal populations in L2/3 of the mouse auditory cortex reportedly exhibit a limited number (1-3) of stable modes of response, each possibly evoked by multiple complex sounds of variable acoustic features. Stimulation using linear intensity mixing of sounds evoking different response modes revealed an attractor-like dynamic of the underlying representation. These modes of response were hypothesized to represent the neural correlate of perceptual categorization. We have developed an experimental protocol enabling chronic two-photon imaging of the previously described population coding under awake conditions. Using this protocol we acquired data suggesting that the pattern of population activity underlying a mode of response, is stable during a week-long timeframe. We have also recorded the neural activity of a local subpopulation of somatostatin-positive inhibitory interneurons (SST+ INs) during abrupt changes in cortical representation. Our preliminary results suggest that local SST+ INs exhibit maximal firing when the neural correlate of a mode of response is exhibited by the surrounding population of principal cells. In addition, we observed a...
|
|
|
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...
|
|
| |
guest ::
RSS feed.