FENS Forum 2010 - Amsterdam

- Posters
To be on display from 8:00 to 13:15 in the morning and from 13:30 to 18:45 in the afternoon.
Poster sessions run from 09:30 to 13:15 in the morning and from 13:30 to 17:30 in the afternoon.
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First author: Hajnik, Tünde (poster)

Poster board E9 - Tue 06/07/2010, 12:15 - Hall 1
Session 143 - Biological rhythms and sleep 2
Abstract n° 143.9
Publication ref.: FENS Abstr., vol.5, 143.9, 2010

Authors Hajnik T., Nagy B., Tóth A. & Détári L.
Address ELTE Dept. of Physiol. and Neurobiol., Budapest, Hungary
Title Homeostatic aspects of the slow cortical rhythm investigated by sleep deprivation
Text Deep sleep is a homeostatically regulated process: in most species sleep pressure increases as a function of time of previous wakefulness and decreases in the course of sleep. The best characterized physiological indicator of sleep intensity is the level of electroencephalogram (EEG) delta power. The EEG slow waves during deep sleep originate from alternating periods of activity and silence of the corticocortical and thalamocortical networks. By monitoring frequency, amplitude and duration of slow cortical waves, locating their current sources and sinks in different cortical layers and recording pyramidal cell activity simultaneously, under control conditions and then following sleep deprivation, we could get deeper insight into homeostatically regulated aspects of deep sleep.
All measured variables of down states changed, but the number of down states was best correlated with delta power changes after deprivation. Correlation between delta power and down state frequency strengthened significantly after sleep deprivation. Multiunit activity increased, then decreased, and then increased again during EEG slow waves. These changes apparently preceded EEG slow wave peaks. Sleep deprivation was followed by less pronounced MUA activity increase after slow waves. Simultaneously to the decrease in MUA activity and general field potential hyperpolarization shifts, strong sinks appeared in layer II/III and in deep layer VI with corresponding sources located in layer III/IV and in layer V. All sinks and sources become stronger following sleep deprivation, but their spatial and temporal distribution was only mildly changed.
It seems that sleep drive is manifested mainly by the more intense potency of downstate inducing (and/or weakening of upstate maintaining) processes. Current sink and sources underlying cortical slow waves are strengthened when sleep propensity is elevated although MUA activity changes before and during slow waves seem mostly independent of the sleep need.
Theme E - Homeostatic and neuroendocrine systems
Biological rhythms and sleep / Sleep: systems and behaviour

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