The study investigated whether specific changes in phase synchrony in the beta 2 frequency band of EEG (25-35 Hz) occurred during a recognition task. The level of synchrony was examined between one hundred and eighty loci in the frontal and temporal lobes of eight epileptic patients with intracerebral electrodes; the EEG records were obtained during a visual oddball task. In each pair of records, the correlation curves were created from the sequence of correlation coefficients calculated. These curves consisted of irregular oscillations between the maximal and minimal r-values. Transient highly synchronized activity was observed during the whole time course of the experiment in all record pairs investigated and a significant relationship was found between the number of such episodes and the mean correlation coefficient (Spearman R 0.84; N 3240; p<0.001). On averaged curves, which were calculated using stimulus onsets as the trigger of averaging, a significant increase of the mean correlation coefficient in the post-stimulus epoch was found (p<0.01 after both target and non-target stimuli; t-test for dependent samples). As the cognitive demand significantly increases after stimulus presentation, the results are considered to be the first evidence from intracranial recording of increased synchronization in the beta 2 frequency band related to the cognitive activity., M. Kukleta ... [et al.]., and Obsahuje seznam literatury
In the mammalian neocortex, the calcium-binding protein calretinin is expressed in a subset of cortical interneurons. In the recent years, research on interneurons is one of the most rapidly growing fields in neuroscience. This review summarizes the actual knowledge of the functions of calretinin in neuronal homeostasis and particularly of the distribution, connectivity and physiological properties of calretinin expressing interneurons in the neocortex of rodents and primates, including humans. The possible neuroprotective role of calretinin and the presumed “resistance” of calretinin-expressing interneurons to various pathological processes are also discussed., F. Barinka, R. Druga., and Obsahuje bibliografii a bibliografické odkazy
Sleep is regulated by complex biological systems and environmental influences, neither of which is fully clarified. This study demonstrates differential effects of partial sleep deprivation (SD) on sleep architecture and psychomotor vigilance task (PVT) performance using two different protocols (sequentially) that each restricted daily sleep to 3 hours in healthy adult men. The protocols differed only in the period of sleep restriction; in one, sleep was restricted to a 3-hour block from 12:00 AM to 3:00 AM, and in the other, sleep was restricted to a block from 3:00 AM to 6:00 AM. Subjects in the earlier sleep restriction period showed a significantly lower percentage of rapid-eye-movement (REM) sleep after 4 days (17.0 vs. 25.7 %) and a longer latency to the onset of REM sleep (L-REM) after 1 day (78.8 vs. 45.5 min) than they did in the later sleep restriction period. Reaction times on PVT performance were also better (i.e. shorter) in the earlier SR period on day 4 (249.8 vs. 272 ms). These data support the view that earlier-night sleep may be more beneficial for daytime vigilance than later-night sleep. The study also showed that cumulative declines in daytime vigilance resulted from loss of total sleep time, rather than from specific stages, and underscored the reversibility of SR effects with greater amounts of sleep., H. Wu ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Ionotropic glutamate receptors function can be affected by neurosteroids, both positively and negatively. N-methyl-D-aspartate (NMDA) receptor responses to exogenously applied glutamate are potentiated or inhibited (depending on the receptor subunit composition) by pregnenolone sulphate (PS) and inhibited by pregnenolone sulphate (3α5βS). While PS effect is most pronounced when its application precedes that of glutamate, 3α5βS only binds to receptors already activated. Synaptically activated NMDA receptors are inhibited by 3α5βS, though to a lesser extent than those tonically activated by exogenous glutamate. PS, on the other hand, shows virtually no effect on any of the models of synaptically activated NMDA receptors. The site of neurosteroid action at the receptor molecule has not yet been identified, however, the experiments indicate that there are at least two distinct extracellularly located binding sites for PS mediating its potentiating and inhibitory effects respectively. Experiments with chimeric receptors revealed the importance of the extracellular loop connecting the third and the fourth transmembrane domain of the receptor NR2 subunit for the neurosteroid action, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptors are inhibited by both PS and 3α5βS. These neurosteroids also affect AMPA receptors-mediated synaptic transmission, however, in a rather indirect way, through presynaptically located targets of action., M. Sedláček, M. Kořínek, M. Petrovič, O. Cais, E. Adamusová, H. Chodounská, L. Vyklický Jr., and Obsahuje bibliografii a bibliografické odkazy
The aim of the present study was to quantify the effect of multisensory rehabilitation on rats’ cognition after an experimental brain trauma and to assess its possible clinical implications. The complex intermittent multisensory rehabilitation consisted of currently used major therapeutic procedures targeted at the improvement of cognitive functions; including multisensory and motor stimulation and enriched environment. We have confirmed this positive effect of early multisensory rehabilitation on the recovery of motor functions after traumatic brain injury. However, we have been able to prove a positive effect on the recovery of cognitive functions only with respect to the frequency of efficient search st rategies in a Barnes maze test, while results for search time and travelled distance were not significantly different between st udy groups. We have concluded that the positive effects of an early treatment of functional deficits are comparable with the clinical results in early neurorehabilitation in human patients after brain trauma. It might therefore be reasonable to apply these experimental results to human medical neurorehabilitation care., M. Lippert-Grüner ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
This study is supported by the collective project of Department of Circuit Theory in FEE-CTU in Prague and the Department of Paediatric Neurology in 2nd Faculty of Medicine of Charles University in Prague. One of the interests in paediatric neurology is a research on electroclinical syndromes area combined with speech disorders. The aim of our project is, among others, finding a connectivity between children's neurological disorders called developmental dysphasia [2], [3] and the assessment of the degree of perception and impairment of speech. From the point of view the characterisation of language, it is very complicated to determine relevant and irrelevant information about speech and to connect it with a searching target. That is why a part of the project is solved by artificial neural networks (ANNs) with using knowledge of phonetics.
At first the analysis of vowels was researched using the ANN. An initial hypothesis says that developmental dysphasia can influence a shift of formant frequencies in spectral characteristics compared with the formant frequencies of healthy children.
It is necessary to have a comparative voice analysis of healthy children for evaluating the degree of these modifications. Our team created the healthy and ill children's speech databases with a comparative corpus. The healthy children's speech was recorded at kindergartens and on the first level of elementary school. The ill children's speech was recorded at hospital. The children were from 4 to 10 years old. The comparative corpus, which includes isolated vowels, monosyllables and polysyllables, was compiled by neurological specialists as related to medical therapy. The same corpus was used for the comparative analysis of healthy children. Our aim is a vowel recognition and visualisation by a Supervised Self-Organizing Maps - Supervised SOMs, which represent one of the types of the ANNs with better cluster separation based on the Kohonen map, see [1]. Better cluster separation is useful for the visualisation analysis, which is easy for the current user. The Recognition Rate (RR) depends also on the knowledge of the children's voice evolution regularity related to their age and gender. Our main objective is not the highest RR, but to observe its trend. We assume that wrong mapped vowels should be one of the indicators of developmental dysphasia.
The application of the Supervised SOM should prove the ability not only to discriminate healthy and ill children, but also to describe a trend of the neurological disorders with the assistance of repeated three-month recordings during a medical therapy.
The method described in the following text was developed to analyze disordered children speech. The diagnosis of the children is developmental dysphasia. Since developmental dysphasia has impact on children's speech ability, the classification of utterances helps to determine whether treatment and medication are appropriate. The paper describes the method developed to provide classification based on utterances but without any additional demands on speech preprocessing (e.g. labeling). The method uses Matching Pursuit algorithm for speech parameterization and Kohonen Self-Organizing Maps for extraction of features from utterances. Features extracted from the utterances of healthy children are then compared to features obtained from the speech of children suffering from the illness.