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Crossing the channel: Surprising new findings in the neurology of sleep and vigilance

Posted on December 31, 2013
Crossing the channel: Surprising new findings in the neurology of sleep and vigilance

Sleep spindles during NREM sleep in CaV3.1+/+ (WT) and CaV3.1−/− (KO) mice. (A) Sample traces show the raw (upper trace) and filtered (lower trace) EEG signals recorded during NREM sleep. Bandpass-filtered (6–15 Hz) EEG signals clearly show spindle events (arrowheads) in both genotypes. (B) There were no differences in the mean length of each spindle episode, number of episodes, mean peak-to-peak amplitude, and peak frequency between CaV3.1+/+ (WT) and CaV3.1−/− mice. Copyright © PNAS, doi:10.1073/pnas.1320572110
A recent neurological addressing one of the most fundamental issues in sleep rhythm generation study underscores an inconvenient truth—namely, that established scientific facts have and will continue to change. Researchers at Institute for Basic Science (Daejeon), Korea Institute of Science and Technology (Seoul) and Yonsei University (Seoul) have demonstrated significant exceptions to the theory, long accepted as dogma, that low-threshold burst firing mediated by T-type Ca2+ channels in thalamocortical neurons is the key component for sleep spindles. (AT-type Ca2+channel is a type of voltage-gated ion channel that displays selective permeability to calcium ions with a transient length of activation. Burst firing refers to periods of rapid neural spiking followed by quiescent, silent, periods. Sleep spindlesare bursts of oscillatory brain activity visible on an EEG that occurs during non-rapid eye movement stage 2, or NREM-2, sleep, during which no eye movement occurs, and dreaming is very rare.) The scientists presented both in vivo and in vitro evidence that sleep spindles are generated normally in the absence of T-type channels and burst firing (periods of rapid neural spiking followed by quiescent, silent, periods) in thalamocortical neurons. Moreover, their results show what they describe as a potentially important role of tonic (constant) firing in this rhythm generation. They conclude that future studies should be aimed at investigating the detailed mechanism through which each type of thalamocortical oscillation is generated.

Read more at: MedicalXpress

   
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