Scientists Think They Found a ‘Minimum Mechanism’ Required for Consciousness

Scientists have identified a tiny area of the brain that plays a critical role in consciousness. According to a study that involved macaque monkeys, electrically stimulating a certain part of the forebrain wakes monkeys from anesthesia.

The researchers found that the central lateral thalamus appears to be one of the “minimum mechanisms” driving consciousness.

The discovery may help researchers in the 21st-century device treatments of consciousness disorders, bring people out of comas, or make sure patients stay unconscious during sensitive procedures.

The central lateral thalamus responsible for consciousness – Scientists

One of the key questions in the neuroscience field is clearly determining which part of the brain is responsible for consciousness. Consciousness is the ability to experience internal and external sensations.

In an article published in the journal Neuron, researchers report that a specific area in the brain, the central lateral thalamus, seems to play a key role in enabling consciousness.

According to Science Daily, in previous studies such as electroencephalogram (EEG) and Functional magnetic resonance imaging (fMRI), neuroscientists found that certain parts of the brain, including the thalamus and the parietal cortex, were involved in consciousness to a certain extent.

In the study, a team of scientists led by first author Michelle Redinbaugh, a graduate student in the Department of Psychology at the University of Wisconsin, Madison, used electrodes to stimulate various parts of the brains of two macaque monkeys.

A study on monkeys found that stimulating a certain part of the forebrain wakes monkeys from anesthesia.
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Note that the brains of Macaque monkeys closely mirror human brains. This makes them ideal models for studying the drivers of consciousness.

One of the researchers Yuri Saalmann, an assistant professor at the university said:

We decided to go beyond the classical approach of recording from one area at a time. We recorded from multiple areas at the same time to see how the entire network behaves.

By electrically stimulating the brains of awake, sleeping, and anesthetized monkeys, they were able to narrow down which parts were involved in consciousness to a much more specific area than previous studies had done.

The objective was to identify the “minimum mechanisms” necessary for driving consciousness. To do that, they ruled out some areas that had been suggested in previous studies, ultimately focusing on the central lateral thalamus, which is located deep in the forebrain.

Once they narrowed down to this area, the scientists then studied what happened when it was activated while the animals were under anesthesia. The central lateral thalamus was stimulated with a frequency of 50 Hz.

Saalmann said:

We found that when we stimulated this tiny little brain area, we could wake the animals up and reinstate all the neural activity that you’d normally see in the cortex during wakefulness. They acted just as they would if they were awake. When we switched off the stimulation, the animals went straight back to being unconscious.

To test wakefulness, the animals were studied to see how they would respond to oddball auditory stimulation – a series of beeps interspersed with other random sounds.

The findings show that the monkeys reacted in the same way that they would respond when they are awake.

Implications For The Future

The team said that there were many “exciting” implications for the study stating that the “kinds of deep-brain stimulating electrodes” used on the monkeys could be used “to bring people out of comas.”

Redinbaugh said:

The overriding motivation of this research is to help people with disorders of consciousness to live better lives. We have to start by understanding the minimum mechanism that is necessary or sufficient for consciousness so that the correct part of the brain can be targeted clinically.

The scientists also believe that their “findings may also be useful for developing new ways to monitor patients under clinical anesthesia, to make sure they are safely unconscious.”

The study was funded by the National Institutes of Health, a United States-Israel Binational Science Foundation, and a Wisconsin National Primate Research Center pilot grant.

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