Consciousness ‘Trigger’ Discovered in Monkeys’ Brain

Consciousness is still an enigma for scientists. They have no definite information regarding why creatures are at times awake and, at times, asleep, of which engines in the brain are most crucial for a conscious condition.

Now, a team of scientists has discovered an ‘engine of consciousness’ in the brain. This part of the body makes, at least monkeys, wake up from anesthesia. The paper showcases some rather important clues regarding consciousness.

Consciousness Pathways

Utilizing electrodes throughout the brains of awake and sleeping apes, as well as monkeys under various types of anesthesia, the researchers discovered two main pathways in the macaques’ brains for consciousness.

The scientists also found a particular brain region that appears to fuel those pathways, similar to an engine they could start using some advanced jumper cables. The area is known as the central lateral thalamus. However, this doesn’t mean that they have found the place of consciousness in the brain.

“It is unlikely that consciousness is specific to one location in the brain,” said Michelle Redinbaugh, a graduate student in psychology at the University of Wisconsin-Madison and main author of the paper, published on February 12th in the journal Neuron.

Prior studies have already found that staying consciousness is comprised of activity expanded across the whole brain, but her team’s research shows that the central lateral thalamus probably has a main role in this.

What ‘Consciousness’ Means

It is rather crucial to learn that, when it comes to this particular study, ‘consciousness’ talks more or less about being awake.

“The word ‘consciousness’ has many definitions,” said Michael Graziano, a neuroscientist at Princeton University who was not part of the research team that conducted the study. “One way to think about consciousness is from a clinical perspective of wakefulness, arousal, and responsiveness to stimuli. In that sense, sleeping people are not conscious, and people in a coma are also not.”

Also, it is not completely definite why or how people turn back and forth between those states. The research focuses on a simple question: What makes people become conscious?

“There is, however, a different conception of consciousness [that is] much more difficult to study: the subjective experience that comes with some instances of information processing in the brain, the ‘what it feels like’ component of our inner life,” Graziano said. “Studies like the present one do not address this type of consciousness.”

Back in August 2007, scientists from the Weill Cornell Medical College in New York City issued a pioneering research in the journal Nature. One of their patients was hospitalized for a few months while it was in a ‘minimally conscious state’ after they suffered a traumatic brain injury.

The man was unaware of his surroundings most of the time, but sometimes, became more conscious and active. Suggesting that his state might include some ‘underactivation’ of vital pathways in his brain, the researchers implanted electrodes that triggered his central thalamus and reported massive enhancements in his level of consciousness.

Two Key Pathways May Hold the Answer

In the new research that involved monkeys, Redinbaugh and her fellow colleagues did more than that. Using electrodes, the team send tiny electric impulses into various regions of the monkeys’ brains while they were asleep or sedated utilizing a few kinds of anesthesia. Most of the time, the monkeys remained asleep. However, sending an impulse at a particular frequency to the central lateral thalamus made the monkeys wake up, even from a deep state of anesthesia-induced sleep.

“The converging evidence from sleep and multiple forms of anesthesia is particularly impressive since we know these have different mechanisms of action,” Sarah Heilbronner, University of Minnesota neuroscientist who was not involved in the study, said.

Recordings from the animals’ brains as they switched between being asleep and awake enabled scientists to narrow down consciousness to two main elements: one of these key circuits moves sensory information from the thalamus to the central cortex, the brain area that preforms many types of complex thinking. Both that circuit and another network, one that ‘carries feedback about predictions, attention priorities and goals in the reverse direction,’ required to be active for consciousness to work, Redinbaugh said.

The central lateral thalamus, the scientists determined, most probably has a main role in activating and keeping those two pathways as it appears to act as a trigger.

This study is not useful only from a solely scientific view, Redinbaugh said. Understanding how consciousness functions could help enhance anesthesia and conduct to new cures for people suffering from consciousness disorders, similar to the patient in the Weill Cornell Medical College study.

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