Waking up is hard to do: Prefrontal cortex implicated in consciousness

June 21, 2018

ANN ARBOR, Mich. -- Philosophers have pondered the nature of consciousness for thousands of years. In the 21st century, the debate over how the brain gives rise to our everyday experience continues to puzzle scientists. To help, researchers in the University of Michigan Medical School Center for Consciousness Science are working to identify areas of the brain that help us wake up, a basic building block of everyday consciousness.

In the search for what controls our overall level of consciousness, researchers have traditionally focused on structures in the lower part of the brain. These structures include the brainstem (which regulates vital functions like breathing, blood pressure and heartbeat); the hypothalamus (which is involved in sleep and controlling bodily functions); and the thalamus (which relays information from the senses). George Mashour, M.D., Ph.D., professor in the Department of Anesthesiology and director of the center, decided to look at different areas of the cortex, the upper part of the brain, for its ability to control the level of consciousness.

Recent research in nonhuman primates provides evidence that the prefrontal cortex has a switchboard-like relationship with other areas of the brain, helping to ignite awareness of visual information.

"There has been a debate that has recently intensified as to whether or not the prefrontal cortex -- versus areas farther back -- plays a role in generating conscious experience. We thought that we'd target some of these different areas in the front and back of the brain to see which ones had the ability to control the level of consciousness," he says.

The key to ignition?

Because anesthesia is used to temporarily eliminate conscious experience during medical procedures, it provides the perfect opportunity to test hypotheses about consciousness.

Mashour and lead-author Dinesh Pal, Ph.D., also of the Department of Anesthesiology, anesthetized rats with a common anesthetic used in humans. "We wanted to see what had the causal power to take an unconscious brain receiving ongoing anesthesia and wake it up," says Pal. To test this, they targeted two neurotransmitters that are associated with wakefulness: acetylcholine and norepinephrine.

The team exposed the anesthetized rats' prefrontal and parietal cortex to drugs that ramped up the effect of the neurotransmitters and measured their brain activity and behavior. When exposed to an acetylcholine-receptor activator, their brain waves, normally slow during sleep and anesthesia, sped up. But rats were able to start behaving as though they were awake only with prefrontal cortex stimulation, all while continuing to receive the same level of anesthesia that is used clinically for surgery in humans. These findings were published in the journal Current Biology.

Mashour says their new study "suggests that the prefrontal cortex also has the potential to play a role in coordinating the level of consciousness, possibly through the cholinergic system."

Clinically, these results could be explored for applications in people with disorders of consciousness, such as coma or vegetative states. "Let's say you have a patient in a coma: Could the prefrontal cortex be a site that is modulated to help coordinate events to help improve level of consciousness?" Mashour asks. The implications of this possibility are significant because of the relative accessibility of the prefrontal cortex.

"It's very difficult and dangerous to directly intervene at the level of arousal centers in the brainstem because of its location, small size and nearby vital functions. Maybe the prefrontal cortex is an accessible gateway to some of those other arousal systems that could be leveraged in a clinical setting outside of anesthesia," he says.
-end-
This work was funded by the National Institutes of Health (R01GM098578), and the Department of Anesthesiology, University of Michigan Medical School, Ann Arbor. Physiology doctoral student Jon Dean was co-first author of the article.

Michigan Medicine - University of Michigan

Related Brain Activity Articles from Brightsurf:

Inhibiting epileptic activity in the brain
A new study shows that a protein -- called DUSP4 -- was increased in healthy brain tissue directly adjacent to epileptic tissue.

What is your attitude towards a humanoid robot? Your brain activity can tell us!
Researchers at IIT-Istituto Italiano di Tecnologia in Italy found that people's bias towards robots, that is, attributing them intentionality or considering them as 'mindless things', can be correlated with distinct brain activity patterns.

Using personal frequency to control brain activity
Individual frequency can be used to specifically influence certain areas of the brain and thus the abilities processed in them - solely by electrical stimulation on the scalp, without any surgical intervention.

Rats' brain activity reveals their alcohol preference
The brain's response to alcohol varies based on individual preferences, according to new research in rats published in eNeuro.

Studies of brain activity aren't as useful as scientists thought
Hundreds of published studies over the last decade have claimed it's possible to predict an individual's patterns of thoughts and feelings by scanning their brain in an MRI machine as they perform some mental tasks.

A child's brain activity reveals their memory ability
A child's unique brain activity reveals how good their memories are, according to research recently published in JNeurosci.

How dopamine drives brain activity
Using a specialized magnetic resonance imaging (MRI) sensor that can track dopamine levels, MIT neuroscientists have discovered how dopamine released deep within the brain influences distant brain regions.

Brain activity intensity drives need for sleep
The intensity of brain activity during the day, notwithstanding how long we've been awake, appears to increase our need for sleep, according to a new UCL study in zebrafish, published in Neuron.

Do babies like yawning? Evidence from brain activity
Contagious yawning is observed in many mammals, but there is no such report in human babies.

Understanding brain activity when you name what you see
Using complex statistical methods and fast measurement techniques, researchers found how the brain network comes up with the right word and enables us to say it.

Read More: Brain Activity News and Brain Activity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.