Half-asleep rats look wide awake

[thinker_jeff]

Some parts of a rat’s brain can fall asleep even while the animal plays and seems wide awake, a new study shows.

 

Researchers at the University of Wisconsin–Madison and their colleagues in Italy kept rats up four hours past the rodents’ usual bedtime. Even though the rats stayed awake, electrodes implanted in their brains showed that some brain cells went to sleep while neighboring ones remained active, the team reports in the April 28 Nature.

 

Rats with sleeping neurons were also prone to making mistakes during slightly difficult tasks, a finding that may have implications for sleep-deprived people.

 

“And it would be very insidious because nobody would be able to tell there was anything wrong with you,” says Giulio Tononi, the University of Wisconsin neuroscientist who led the work. The rats in the study weren’t “staring off into the void or anything,” he says.

 

The findings add to a growing body of evidence that sleep doesn’t necessarily involve the whole brain at one time. Many scientists previously thought that a central control center determined when the brain sleeps and wakes. But researchers have been building a case for the past two decades that sleep may originate in single cells and eventually spread all over the brain.

 

As far as the researchers could tell, the rats were fully awake and playing with objects the researchers had supplied to keep the animals up past their bedtimes. Only the electrodes implanted in two parts of the brain recorded the neuron naps.

 

But just because the rats weren’t nodding off doesn’t mean their brains were working well. The team tested the sleep deprived rats’ ability to reach through a plexiglass wall and grasp a sugar cube. The task involves some coordinated moves, such as rotating the wrist, that aren’t part of a rat’s normal repertoire, so if the animals’ brains aren’t firing on all cylinders, the grab could fail.

 

When brain cells in the motor cortex — a part of the brain that controls movement — fell asleep, rats failed in attempts to grab the sugar cubes for several hundred milliseconds afterward. But sleeping neurons in the parietal cortex, which is not involved in the task, did not lead to mistakes.

 

If the finding applies to people it could mean that lost sleep is even more dangerous than previously believed, leading to slips of the tongue, driving mistakes, errors of judgment or other problems.

 

“So many humans are walking around with a sleep debt,” says Christopher Colwell, a neuroscientist at UCLA. “This is probably part of the everyday situation for a lot of people.”

 

Link: http://www.sciencenews.org/view/generic/id/73636/title/Half-asleep_rats_look_wide_awake

 

 

 

[Joshua201]

Some parts of a rat’s brain can fall asleep even while the animal plays and seems wide awake, a new study shows.

 

Researchers at the University of Wisconsin–Madison and their colleagues in Italy kept rats up four hours past the rodents’ usual bedtime. Even though the rats stayed awake, electrodes implanted in their brains showed that some brain cells went to sleep while neighboring ones remained active, the team reports in the April 28 Nature.

 

Rats with sleeping neurons were also prone to making mistakes during slightly difficult tasks, a finding that may have implications for sleep-deprived people.

 

“And it would be very insidious because nobody would be able to tell there was anything wrong with you,” says Giulio Tononi, the University of Wisconsin neuroscientist who led the work. The rats in the study weren’t “staring off into the void or anything,” he says.

 

The findings add to a growing body of evidence that sleep doesn’t necessarily involve the whole brain at one time. Many scientists previously thought that a central control center determined when the brain sleeps and wakes. But researchers have been building a case for the past two decades that sleep may originate in single cells and eventually spread all over the brain.

 

As far as the researchers could tell, the rats were fully awake and playing with objects the researchers had supplied to keep the animals up past their bedtimes. Only the electrodes implanted in two parts of the brain recorded the neuron naps.

 

But just because the rats weren’t nodding off doesn’t mean their brains were working well. The team tested the sleep deprived rats’ ability to reach through a plexiglass wall and grasp a sugar cube. The task involves some coordinated moves, such as rotating the wrist, that aren’t part of a rat’s normal repertoire, so if the animals’ brains aren’t firing on all cylinders, the grab could fail.

 

When brain cells in the motor cortex — a part of the brain that controls movement — fell asleep, rats failed in attempts to grab the sugar cubes for several hundred milliseconds afterward. But sleeping neurons in the parietal cortex, which is not involved in the task, did not lead to mistakes.

 

If the finding applies to people it could mean that lost sleep is even more dangerous than previously believed, leading to slips of the tongue, driving mistakes, errors of judgment or other problems.

 

“So many humans are walking around with a sleep debt,” says Christopher Colwell, a neuroscientist at UCLA. “This is probably part of the everyday situation for a lot of people.”

 

Link: http://www.sciencenews.org/view/generic/id/73636/title/Half-asleep_rats_look_wide_awake

[Basi]

 

I think it would be extremely interesting to note which parts of the brain appeared to be "sleeping" while the rats appeared to be consciously going about their business. AKA what part of the brain evolution has told modern day humans is less important compared to alternative areas.

[DrmDoc]

Some parts of a rat's brain can fall asleep even while the animal plays and seems wide awake, a new study shows.

 

Researchers at the University of WisconsinMadison and their colleagues in Italy kept rats up four hours past the rodents' usual bedtime. Even though the rats stayed awake, electrodes implanted in their brains showed that some brain cells went to sleep while neighboring ones remained active, the team reports in the April 28 Nature.

 

Rats with sleeping neurons were also prone to making mistakes during slightly difficult tasks, a finding that may have implications for sleep-deprived people.

 

"And it would be very insidious because nobody would be able to tell there was anything wrong with you," says Giulio Tononi, the University of Wisconsin neuroscientist who led the work. The rats in the study weren't "staring off into the void or anything," he says.

 

The findings add to a growing body of evidence that sleep doesn't necessarily involve the whole brain at one time. Many scientists previously thought that a central control center determined when the brain sleeps and wakes. But researchers have been building a case for the past two decades that sleep may originate in single cells and eventually spread all over the brain.

 

As far as the researchers could tell, the rats were fully awake and playing with objects the researchers had supplied to keep the animals up past their bedtimes. Only the electrodes implanted in two parts of the brain recorded the neuron naps.

 

But just because the rats weren't nodding off doesn't mean their brains were working well. The team tested the sleep deprived rats' ability to reach through a plexiglass wall and grasp a sugar cube. The task involves some coordinated moves, such as rotating the wrist, that aren't part of a rat's normal repertoire, so if the animals' brains aren't firing on all cylinders, the grab could fail.

 

When brain cells in the motor cortex a part of the brain that controls movement fell asleep, rats failed in attempts to grab the sugar cubes for several hundred milliseconds afterward. But sleeping neurons in the parietal cortex, which is not involved in the task, did not lead to mistakes.

 

If the finding applies to people it could mean that lost sleep is even more dangerous than previously believed, leading to slips of the tongue, driving mistakes, errors of judgment or other problems.

 

"So many humans are walking around with a sleep debt," says Christopher Colwell, a neuroscientist at UCLA. "This is probably part of the everyday situation for a lot of people."

 

Link: http://www.sciencene...look_wide_awake

Sleep deprivation has been studied ad nauseum over many years. A quick Google Scholar (GS) search returned over 54,000 such studies between 1992 and 2011 alone. Among the thousands of papers and studies I've personally reviewed on sleep not a single one suggested or showed unihemispheric sleep in humans under any circumstance. Even with a GS search, I did not find any reference to such sleep behaviors in humans with intact brains. If it were possible under sleep deprivation, unihemispheric sleep in humans would have been determined decades ago. Although I did not read the article, it is unlikely that the discovery of unilateral sleep--evoked by sleep deprivation--in the brains of rats has any implication for similar sleep processes or behaviors in humans. I question the validity of rat studies of sleep deprivation when human study provides the most direct and relatable evidence to humans even in extreme cases such as fatal familial insomnia.

Edited May 27, 2011 by DrmDoc

[michel123456]

It reminds me a study about half asleep ducks.

[Marat]

What about the relation of this phenomenon in rats to highly sophisticated activity by human sleep-walkers who are not in the least conscious of what they have done when they are later woken up? There is even an English case, R. v. Harvey, of someone who murdered his wife while sleep-walking, put the body in the trunk of his car, drove off to the woods, hid the body in the forest, and drove back home, undressed, and got back into bed without even knowing what he had done. The court accepted his sleep-walking defense as proved, despite the best efforts by the Crown to convict.

[DrmDoc]

What about the relation of this phenomenon in rats to highly sophisticated activity by human sleep-walkers who are not in the least conscious of what they have done when they are later woken up? There is even an English case, R. v. Harvey, of someone who murdered his wife while sleep-walking, put the body in the trunk of his car, drove off to the woods, hid the body in the forest, and drove back home, undressed, and got back into bed without even knowing what he had done. The court accepted his sleep-walking defense as proved, despite the best efforts by the Crown to convict.

Court opinion notwithstanding, there has never been a proven case of unihemispheric sleep in humans with intact brains. Although there have been some court cases where somnambulism was used as a successful defense for murder, I never believed in the validity of such opinions. There are no brain studies in somnambulism which suggests that the brain is engaged in sleep function. In my opinion, the condition is akin to hypnosis wherein the hypnotized engage behaviors they normally would not without the lower inhibitions hypnosis evokes. Murder, even under hypnosis, is still murder in my opinion. Sleep deprived activity in rats is not relatable to somnambulism in humans because there is no evidence of unihemispheric sleep processes in humans as in rats. If the goal is to understand the nature of sleep deprivation and sleep-walking in humans, how are rat studies more relatable than human studies? Are there no humans who experience sleep deprivation and sleep-walking? Other than for vivsection or drug testing purposes, how are rats more suitable for this kind of human-equivalent study?

Edited May 28, 2011 by DrmDoc

[thinker_jeff]

Sleep deprivation has been studied ad nauseum over many years. A quick Google Scholar (GS) search returned over 54,000 such studies between 1992 and 2011 alone. Among the thousands of papers and studies I've personally reviewed on sleep not a single one suggested or showed unihemispheric sleep in humans under any circumstance. Even with a GS search, I did not find any reference to such sleep behaviors in humans with intact brains. If it were possible under sleep deprivation, unihemispheric sleep in humans would have been determined decades ago. Although I did not read the article, it is unlikely that the discovery of unilateral sleep--evoked by sleep deprivation--in the brains of rats has any implication for similar sleep processes or behaviors in humans. I question the validity of rat studies of sleep deprivation when human study provides the most direct and relatable evidence to humans even in extreme cases such as fatal familial insomnia.

The unihemispheric sleep means that one of the hemisphere sleeps while another hemisphere remains awake. But this study doesn't need unihemispheric sleep. Here is the Abstract: http://www.nature.com/nature/journal/v472/n7344/full/nature10009.html

 

"In an awake state, neurons in the cerebral cortex fire irregularly and electroencephalogram (EEG) recordings display low-amplitude, high-frequency fluctuations. During sleep, neurons oscillate between 'on' periods, when they fire as in an awake brain, and 'off' periods, when they stop firing altogether and the EEG displays high-amplitude slow waves. However, what happens to neuronal firing after a long period of being awake is not known. Here we show that in freely behaving rats after a long period in an awake state, cortical neurons can go briefly 'offline' as in sleep, accompanied by slow waves in the local EEG. Neurons often go offline in one cortical area but not in another, and during these periods of 'local sleep', the incidence of which increases with the duration of the awake state, rats are active and display an 'awake' EEG. However, they are progressively impaired in a sugar pellet reaching task. Thus, although both the EEG and behaviour indicate wakefulness, local populations of neurons in the cortex may be falling asleep, with negative consequences for performance."

Edited May 28, 2011 by thinker_jeff

[DrmDoc]

The unihemispheric sleep means that one of the hemisphere sleeps while another hemisphere remains awake. But this study doesn't need unihemispheric sleep. Here is the Abstract: http://www.nature.co...ature10009.html

 

"In an awake state, neurons in the cerebral cortex fire irregularly and electroencephalogram (EEG) recordings display low-amplitude, high-frequency fluctuations. During sleep, neurons oscillate between 'on' periods, when they fire as in an awake brain, and 'off' periods, when they stop firing altogether and the EEG displays high-amplitude slow waves. However, what happens to neuronal firing after a long period of being awake is not known. Here we show that in freely behaving rats after a long period in an awake state, cortical neurons can go briefly 'offline' as in sleep, accompanied by slow waves in the local EEG. Neurons often go offline in one cortical area but not in another, and during these periods of 'local sleep', the incidence of which increases with the duration of the awake state, rats are active and display an 'awake' EEG. However, they are progressively impaired in a sugar pellet reaching task. Thus, although both the EEG and behaviour indicate wakefulness, local populations of neurons in the cortex may be falling asleep, with negative consequences for performance."

Again, there is nothing in the reams of studies on human sleep deprivation that suggest the kind of rolling "offline" brain function observed in sleep deprived rats. The effects of sleep deprivation in humans appear to be brainwide rather than localized. Humans are not well adapted to remain alert when sleep deprived. This seems consistent with a distinction of humans as a species whose survival is not as dependent on continual vigilance as is the survival of other species. This sleep study, in my opinion, merely suggest that the brains of rats appear to be better adapted for sustained periods of vigilance than humans.