Neuronal Activities Underlying the Electroencephalogram and Evoked-Potentials of Sleeping and Waking - Implications for Information-Processing

Contains fulltext : 29051.pdf (publisher's version ) (Open Access

Hypnos en Thanatos : de tijdelijke en de eeuwige slaap

Contains fulltext : 32100_hypnenth.pdf (publisher's version ) (Open Access)With bibliogr., valedictory address Radboud University Nijmegen28 p

De slaap en het bed: een psychobiologische beschouwing

Contains fulltext : 54864-OA.pdf (publisher's version ) (Open Access)Sleep is a main factor for restoration of body and brain. Two main types of sleep can be distinguished: slow wave sleep, with its deep and light sleep, and REM sleep. Deep slow wave sleep, occurring in the first part of the night, is particularly involved in bodily restoration, while light sleep, in the second half of the night, seems to have a more luxury nature. REM sleep, associated with dreaming, occurs in regular periods during the entire night. The duration of sleep varies commonly between 7 and 8 hours. Sleep begins when body temperature decreases and when the light disappears, while sleep ends when body temperature starts to increase and light returns. The temperature in bed is particularly relevant for sleep and must be in the thermoregulatory zone of 27 to 29 degrees Celsius. In falling asleep a preferable sleeping posture is chosen. Despite this favorite position, there are relatively many movements during the night. This keeps the body in a proper condition during the long period of sleep. Bed, pillow and mattress have to permit these movements and have also to facilitate a side-position of the body. The latter is a better position compared to sleeping on belly or back. In particular snoring occurs the least in a side position. In this way a comfortable bed and good bed materials facilitate sleep, as well as an optimally equipped sleeping room without too much noise, a suitable light-dark regime, an acceptable temperature and proper ventilation and humidity

Where is the classic interference theory for sleep and memory? [editorial]

Contains fulltext : 54526.pdf (publisher's version ) (Open Access)Walkers target article proposes a refinement of the well known two-stage model of memory formation to explain the positive effects of sleep on consolidation. After a first stage in which a labile memory representation is formed, a further stabilisation of the memory trace takes place in the second stage. which is dependent on (REM) sleep. Walker has refined the latter stage into a stage in which a consolidation-based enhancement occurs. It is not completely clear what consolidation-based enhancement implies and how it can be dissociated from a stage for memory-stabilisation. A more serious consideration, however, is whether a second stage in memory consolidation that is solely dependent on sleep is really necessary. The classical, passive, interference theory is able to explain adequately the findings related to the effects of sleep and memory, and can lead perhaps better to an understanding of the highly variable data in this field.1 p

Hypnos en Thanathos: de tijdelijke en de eeuwige slaap

Contains fulltext : 73314.pdf (publisher's version ) (Open Access)Farewell address RU, 29 februari 200828 p

Attention enhances positivity in auditory evoked potentials: Evidence for an inhibitory process facilitating stimulus salience

Contains fulltext : 56905.pdf (publisher's version ) (Open Access

Adolf Beck: A pioneer in electroencephalography in between Richard Caton and Hans Berger

Contains fulltext : 122443.pdf (publisher's version ) (Open Access)Adolf Beck, born in 1863 in Kraków (Poland), joined the Department of Physiology of the Jagiellonian University in 1889, to work directly under the prominent professor in physiology Napoleon Cybulski. Following his suggestion, Beck started studies on the electrical brain activity of animals. He recorded negative electrical potentials in several brain areas evoked by peripheral sensory impulses. Using this technique, Beck localised various centres in the brain of several animal species. In doing this, he discovered continuous electrical oscillations in the electrical brain activity and noted that these oscillations ceased after sensory stimulation. This was the first description of desynchronisation in electrical brain potentials. He published these findings in 1890 in the German Centralblatt für Physiologie. Immediately, an intense discussion arose under physiologists on the question who could claim being the founder of electroencephalography. Ultimately, Richard Caton from Liverpool showed that he had performed similar experiments in monkeys years earlier. Nevertheless, Beck added several new elements to the nature of electrical brain activity, such as evoked potentials and desynchronisation. In looking back, Adolf Beck can be regarded, next to Richard Caton and together with Hans Berger (who later introduced the electrical brain recording method to humans), as one of the founders of electroencephalography.6 p

Effects of remacemide and its metabolite FPL 12495 on spike-wave discharges, electroencephalogram and behaviour in rats with absence epilepsy

Contains fulltext : 28626.pdf (publisher's version ) (Open Access)The effects of the anti-convulsant drug remacemide and one of its active metabolites FPL 12495 were examined in a genetic model for generalized absence epilepsy, the WAG/Rij strain of rats. Number, mean and total duration of spike-wave discharges were measured following oral administration of remacemide and FPL 12495, together with parameters of background electroencephalographic activity (EEG) and spontaneous behaviour in the recording cage. A decrease in the number of the spike-wave discharges was found after remacemide administration. At the highest dose there was near total suppression of the spike-wave discharges. There were no important effects on behaviour and on spectral content of the background EEG, suggesting that remacemide has little side effects. A decrease in the number of spike-wave discharges was also found after FPL 12495 gavage and there was a prolongation of the mean duration. Behavioural changes were only noticed after the highest dose. These were accompanied by changes in the spectral content and particularly by an increase in the amplitude of the delta and the high beta frequencies, together with a decrease in the spindle frequency range. FPL 12495 appeared to be more potent that remacemide in all its effects. The effects of mainly FPL 12495 are uncommon in the sense that so far no other investigated drug shows a decrease in the number together with an increase in the mean duration of the discharges. It seems that in contrast to other anti-epileptic drugs, FPL 12495 exerts a differential action on the two commonly distinguished mechanisms controlling number and duration

Modelling of auditory evoked potentials of human sleep-wake states

Item does not contain fulltextThe shape of evoked potentials is influenced by the level of vigilance, varying with sleep–wake states. In this paper the shape of auditory evoked potentials is modelled by taking two factors, both modulating the underlying neuronal substrate, into account: ‘sensory gating’ and ‘neuronal firing mode’. Under low levels of vigilance sensory gating reduces the amount of neuronal activity reaching the cortical centres. Due to a rise in hyperpolarisations of thalamocortical neurons associated with an increasing depth of sleep, stimulus evoked primary and secondary excitations, seen as correlates of the N1 and N2 waves of the evoked potential, become smaller. Heightened hyperpolarisations also change the spontaneous activity of neurons from the ‘tonic’ firing mode of wakefulness into the ‘burst–pause’ firing mode of sleep. The large P220 complex together with the N350 and N550 waves in sleep are caused by the stimulus induced triggering of pauses and bursting of neurons. The results of this modelling experiment confirm the view that sleep-specific components such as P220, N350 and N550 are waves that facilitate and protect sleep, whereas the wake-specific components N1, P2–P3 and N2 have perceptual–cognitive functions. In particular the wake P2–P3 wave is sensitive to cognitive functions, such as attention. Based on the modelling results it is suggested that component negativities, expressed in N1, N2 and N350, reflect excitatory processes, whereas positivity in P2–P3 and P220 is a correlate of inhibitory processes. Hence, the large P3 in an attended condition is also interpreted as an inhibitory process suppressing irrelevant information, facilitation the saliency of relevant information.4 p