Human Consciousness Study Pinpoints areas in the Brain that may be the Source
- Neurologists studied coma patients with injuries to a central brain region
- Lesions in one area of the brain stem were strongly associated with coma
- Injury disrupted connections with regions maintaining consciousness
- Researchers say viewing coma as a network disorder could open up new avenues of treatment, such as electrical brain stimulation, for patients
The question of where human consciousness originates has been mulled over by philosophers, spiritualists, and artists for thousands of years.
Now neuroscientists think they have moved closer to an answer, by uncovering the areas of the brain involved in maintaining it.
By studying coma patients with injuries in the very center of their brains, US doctors have uncovered the intricate connections between regions which keep us awake and aware, both core components of consciousness.
Neurologists studying coma patients with injuries in their brain stems (tail-like region which connects the brain to the spinal cord, pictured) have uncovered the network of regions which keep us awake and make us aware, both core components of human consciousness
For humans, the regulation of basic functions like sleeping, breathing and heart rate, is kept ticking over automatically by the brain stem.
This thick trunk of nerve tissue, nestled in the center of the brain, connects to the spinal cord and is responsible for rousing us from slumber.
Awareness is thought to be a higher brain function, controlled by the cortex – the outermost layer of the brain associated with more advanced functions, such as speech, thought and action.
In certain types of brain injury, consciousness can become disrupted, with the patients slipping into a coma.
The team says that seeing coma as a network disorder of how these regions communicate, rather than just damage to a single area, could potentially open up new avenues of treatment, such as electrical brain stimulation (stock image used)
COMA PATIENTS REVEAL SEAT OF CONSCIOUSNESS
Neurologists in the US studied a number of patients with lesions in their brain stem, a number of which resulted in a coma.
They found that not only were a high proportion of lesions in the same region in coma patients but that they affected communication with two other regions of the brain.
Both regions have previously been identified as key in keeping us awake and making us aware – core components of human consciousness
The researchers say that seeing coma as a network disorder of how these regions communicate, rather than just damage to a single area, could potentially open up new avenues of treatment, such as electrical brain stimulation.
Researchers at the Beth Israel Deaconess Medical Center (BIDMC) in Massachusetts focused on a subset of these coma-inducing injuries, affecting the brain stem.
They looked at 36 patients with lesions in the brain stem, 12 of which resulted in a coma.
Scans revealed that in the coma patients, 10 of them had lesions in the same part of the brain stem, in a region called the dorsolateral pontine tegmentum (DPT), while only one of the 24 non-coma patients had a lesion in the same area.
Using the scans they were able to map the DPT and its functional connections to see which other brain areas were implicated in a coma.
They found two regions previously associated with awareness and arousal, the anterior insular (AI) and the pregenual anterior cingulate cortex (pACC).
‘For the first time, we have found a connection between the brain stem region involved in arousal and regions involved in awareness, two prerequisites for consciousness,’ said Dr Michael Fox, a neurologist at BIDMC and an assistant professor at Harvard Medical School.
Writing in the journal Neurology, Dr Fox and team explain that this network of brain regions may have a role in maintaining human consciousness.
According to the researchers, looking at how brain regions functionally connect to one another has helped to understand a range of neurological conditions, including hallucinations as well as speech and movement disorders (stock image used)
The findings mean should move their focus beyond just the injured brain stem region to the other areas they are connected to.
According to the team, this approach of looking at how the regions connect to one another has helped to understand a range of neurological conditions, including hallucinations as well as speech and movement disorders.
Applying the same thinking to coma patients, seeing it as a disorder of how the regions communicate, rather than just damage to a single area, could potentially open up new avenues of treatment, such as electrical brain stimulation.
Dr Fox added: ‘This is most relevant if we can use these networks as a target for brain stimulation for people with disorders of consciousness.
‘If we zero in on the regions and network involved, can we someday wake someone up who is in a persistent vegetative state? That’s the ultimate question.’
PINPOINTING ‘FREE WILL’ IN THE BRAIN
Earlier this year neuroscientists in the US claimed to have caught the brain in the act, capturing the activity right at the point it makes a decision – effectively pinpointing free will in the brain.
Using functional MRI scans, scientists showed which brain regions had a surge in activity before a free decision is made.
Each time a person switched their view from one screen to another at will during the experiment, increased activity was seen in spots of the frontal and parietal lobes, which the team believes indicates where choice is being made in the brain.
They conclude that when participants were left to their own devices, the activity in the frontal lobe started much earlier than if they would have been instructed, indicating the choice was voluntary.