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