When the region of the brain, called the claustrum, is electrically stimulated, consciousness — self-awareness, sentience, whatever you want to call it — appears to turn off completely. (Click Image To Enlarge)
Researchers at George Washington University are reporting that they’ve discovered the human consciousness on-off switch, deep within the brain. When this region of the brain, called the claustrum, is electrically stimulated, consciousness — self-awareness, sentience, whatever you want to call it — appears to turn off completely. When the stimulation is removed, consciousness returns. The claustrum seems to bind together all of our senses, perceptions, and computations into single, cohesive experience. This could have massive repercussions for people currently in a minimally conscious state (i.e. a coma), and for deciding once and for all which organisms are actually conscious. Are monkeys conscious? Cats and dogs? A fetus?
When it comes to human consciousness, much like the rest of our brain’s operation, there isn’t a whole lot in the way of actual scientific knowledge. Despite a century of “modern” neuroscience, we still only have a rough sketch of how the human brain works. Most theories, though, generally agree that consciousness is probably created by a part of the brain that integrates activity from different regions of the brain into a single, holistic experience. To put it in (very loose) computing terms, this seat of human consciousness would be somewhat like a CPU; without it, you’d just have a bunch of different parts that are theoretically functional, but not really capable of getting anything useful done.
The claustrum, below the neocortex, in a human brain (Click Image To Enlarge)
The research, led by Mohamad Koubeissi at GWU in Washington DC, was originally tasked with analyzing a woman with epilepsy. The neuroscientists were stimulating regions of the brain with electrodes in an attempt to discover where her seizures originated from. Then, when they stimulated the claustrum — a thin region of the brain underneath the neocortex — the patient slowly lost consciousness. When the stimulation was removed, consciousness returned. When the claustrum was stimulated, the woman just stopped whatever she was doing (speaking, reading, moving) and stared blankly into space; when stimulation was removed, she continued as normal with no recollection of what had just happened. [DOI: 10.1016/j.yebeh.2014.05.027 – “Electrical stimulation of a small brain area reversibly disrupts consciousness”]
Speaking to New Scientist, Koubeissi said:
“I would liken it to a car. A car on the road has many parts … but there’s only one spot where you turn the key and it all switches on and works together. So while consciousness is a complicated process created via many structures and networks – we may have found the key." Read: Human consciousness is simply a state of matter, like a solid or liquid – but quantum.
As you might expect when it comes to bleeding-edge neuroscience, there are some caveats to the research — most notably, the study only looked at the brain of one person, and due to her epilepsy (and previous removal of part of her hippocampus) she doesn’t necessarily represent a “normal” brain. In short, more research needs to be done — and following the publishing of this paper, you can be guaranteed that there will be more research into the claustrum.
COMMENTARY: While most of us automatically identify the brain as the headquarters of our awareness, neuroscientists seek a more precise location (and understanding) for this unique if everyday phenomenon. A new study by neuroscientists of Vanderbilt University finds that consciousness does not make its home in just one brain region. Instead, researchers say, awareness degrades the brain’s modular function and substitutes an integrated connectivity in which widespread communication arises across areas of the cortex. Consciousness, then, arises from cooperative and not solo brain activity.
Since the beginning of thought, philosophers have wondered where we derive our consciousness, and with the advent of sophisticated imaging technologies, neuroscientists have begun to explore this question in steadily increasing depth. Most recently, a 2014 study suggested that one region of the brain works as an on/off switch for awareness — when researchers electrically stimulated the claustrum of a patient (see video below), she instantly became unconscious. While this experiment does not prove consciousness resides in the claustrum, it raised many questions about the function of this unusual brain region: a thin, irregular structure of neurons hidden beneath the surface of the neocortex.
Francis Crick and Christof Koch, two pioneers in the field of human consciousness, theorize the claustrum functions as “a conductor coordinating a group of players in the orchestra, the various cortical regions.” Their hypothesis is based on the fact that the claustrum receives input from — and projects back to — almost all regions of the outside layer of the brain, the cortex.
Graphs and Images
For the current study, Vanderbilt University researchers investigated whether one or just a few areas of the brain might produce awareness. To accomplish their work, they used graph theory, a branch of mathematics focused on understanding highly complex, advanced networks, and a simple brain imaging experiment.
The experiment began with participants lying down on the hard bed of an MRI scanner. While researchers observed, participants performed a simple task of detecting a disk as it briefly flashed on the screen before them. After each participant completed a number of trials, the researchers compared all the results. They labeled those tests when participants detected the disk as “aware” and those when they missed the disk as “unaware.”
Upon analysis, the researchers discovered that no one area or network of areas in the brain stood out as particularly active during awareness. In fact, the whole brain appeared to become more connected following each report of awareness. The authors wrote.
“These results provide compelling evidence that awareness is associated with truly global changes in the brain’s functional connectivity.”
Douglass Godwin, one of the authors of the study and a graduate student at Vanderbilt, told KurzweilAI.
“We take for granted how unified our experience of the world is. We don’t experience separate visual and auditory worlds; it’s all integrated into a single conscious experience. This widespread cross-network communication makes sense.”