How the Brain Awakens from Unconsciousness Becomes Clearer
Research on rats suggests the path the brain takes to regain consciousness may be even more sophisticated than thought.
Exactly what happens when people wake up from anesthesia or a coma has long baffled scientists, but now new research on rats suggests the path the brain takes to regain consciousness may be even more sophisticated than thought.
"It is commonly assumed that waking from anesthesia is a simple thing: The drugs leave the brain, and the effects they produced in the brain get washed out, and the brain somehow recovers," said Dr. Alex Proekt, an assistant professor of anesthesiology at Weill Cornell Medical College in New York. "But that 'somehow' part is poorly understood."
The researchers looked at the brain's activity patterns, hypothesizing that the activity follows a structured path, changing in a specific way as the brain moves toward consciousness. The researchers wanted to know whether the brain moves from one activity state to the next, in a stepwise fashion, or whether the brain can go from any given state to a number of other states, and therefore, that there are multiple routes to consciousness.
To examine the brain's trajectory while recovering consciousness, Proekt and colleagues recorded the electrical activity of certain brain regions in anesthetized rats. They slowly lowered the concentration of anesthetic vapor that the animals were breathing, until they eventually woke up.
The analysis of the rats' brain activity suggested that the brain passes through several distinct activity states to become conscious. The researchers found that only certain transitions between activity states are possible, and some states do form hubs that connect groups of otherwise disconnected states. [10 Things You Didn't Know About the Brain]
"Although many paths through the network are possible, to ultimately enter the activity state compatible with consciousness, the brain must first pass through these hubs in an orderly fashion," the researchers wrote in their study published today (June 9) in the Proceedings of the National Academy of Sciences.
Trapped in a coma The researchers said the new findings could one day be used to help people in a coma. The brains of people under anesthesia as well as comatose patients show an electrical pattern known as burst suppression, which is characterized by periods of spikes in activity, alternating with periods of silence.
Both general anesthesia and coma are major perturbations to brain's normal activity, and in some cases, the brain cannot find its way back to consciousness.
"Some people, after injury, will remain in some minimally conscious state forever, but some people can recover years after the injury," Proekt said.
"One interesting possibility is that perhaps the injury can act to remove some of these loops, so in a sense you are trapped in one of these states," Proekt told Live Science.
In order to help comatose patients, scientists will first have to examine whether the same phenomenon they observed in rats also exists in the human brain, and then explore how it may be possible to push the brain out of one state so it can proceed further toward recovery, Proekt said.
Awake during surgery Although anesthesiologists have long been able to successfully put people to sleep, they still can't be 100 percent sure that a patient is truly unconscious, rather than just unable to respond.
Understanding the transitions between activity states that happen during the brain's recovering from anesthesia may be the first step to finding a way to detect when someone is on the verge of waking up, Proekt said.
"It's not a common problem, but it is a petrifying scenario to imagine -- being paralyzed and awake for surgery," he said.
Studies have suggested that a very small number of patients experience awaking during surgery, but it is also possible that a larger number of people have some awareness during surgery but don't recall afterwards, Proekt said.
Original article on Live Science.
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The path back from consciousness may be more complex than we realized.
Method of Treating Corpses, John H. Chambers: July 8, 1890
A decade before the turn of the century, John H. Chambers submitted a patent to systematically remove decomposition fluid from caskets -- which no longer needed to be buried, given his upright, contained design:
"I am aware that it is not new to provide for the removal from the coffin of the fluid in a matter created by the decomposition of the body, and I do not seek to cover such, broadly. Neither do I claim, broadly, the process of embalming, as I am aware that it has long been the practice to embalm bodies after death; but so far as I am aware it never has been proposed to embalm the body and then provide for the exclusion of the air and the removal of the fluid matter from the coffin. This is important. I also attach importance to the employment of the disinfecting-trap in the outlet-pipe to the coffin."
Improvement in Poison Bottles: James W. Bowles; Oct. 10, 1876
During the 19th century, losing your poison among the assortment of other -- non-lethal -- liquids and tonics in your collection was evidently a common mishap. Or at least James W. Bowles thought as much, so he set out to solve that problem in 1876 with his coffin-shaped bottles.
Bowles explains in his patent: "(T)he peculiar shape of the bottle serves as a warning against the careless use of the contents."
Method of Preserving Corpses: Graham Hamrick; Jan. 5, 1892
Can a torch of burning sulfur really keep a body from decomposing? Graham Hamrick thought so.
In 1888, Hamrick devised a complicated process of embalming that included a plethora of chemicals and a burning sulfur torch that needed to be relit on a regular basis.
The record shows it took more than four years for his patent to be approved, but Hamrick defended his process:
"Subjects preserved by my procedure above set forth involving treatment for the longer period of about 40 days have been kept for many months through the hottest weather, in the open air, in a perfectly natural condition, and without any decomposition. I am unable to assign any limit to the continual preservation of such embalmed bodies."
Corpse Eye Closer: J.M. Spear; April 21, 1891
It turns out that "effectually adjusting and closing the eyelids of corpses in such manner as to impart thereto an undisturbed or natural appearance," was a difficult feat to perform in 1891 when J.M. Spear applied for a patent for his "Corpse Eye Closer."
Spear's contraption, a rounded piece of metal with sharp, angled teeth, is meant to be slipped between the eyeball and the eyelid of the deceased.
Improvement in Combined Grave, Coffin and Monument: Leland M. Speers and Abraham Clark; July 6, 1875
Three for the price of one! Leland M. Speers and Abraham Clark sought to bring simplicity to the 19th-century burial -- and an added safety feature in case someone was buried alive.
In the gentlemen's own words: "(T)he features of the dead can be viewed at any time without removing the cover. This enables friends of the deceased who may have been absent at the time of the death and funeral to view the said deceased at any time they may wish. This construction also enables the body to be watched for any desired length of time, in cases where there may be doubt as to whether the body may be dead or in a trance state, until it revives or all doubt is removed."
Buried Alive Prevention
Being buried alive might be less of a concern today, but it was a real possibility in the 19th century, as evidenced by various patents from the era.
Many of these elaborate contraptions include all bells and whistles -- sometimes literally -- to prevent such mistakes. One even includes an air shaft to ensure proper breathing while the living soul awaits retrieval. Another is designed so that the mistakenly deceased must hit his or her head on the coffin to call for help.
Beheading Block and Ax: William Hanlon; Feb. 11, 1890
William Hanlon's patented Beheading Block and Ax is not nearly as deadly as it sounds. In fact, it's a turn-of-the-century magic trick.
Hanlon writes: "The object of this invention is to produce upon the stage in the presence of an audience and under full light an illusive beheading so nearly realistic that as the victim's head lies upon the block the descending ax and block give forth the natural thud of a blow, and the blade appears to actually sever the neck of the victim, and after the seeming separation of the head from the body both simultaneously fall, the body to the floor and the head apparently through the block to an opening at the base thereof at a point removed from its natural position, both in distance and angle, and all this without the employment of reflectors, such as are commonly used for illusive acts of this general character."