In an article in The Atlantic titled “Awakening” Joshua Lang describes how patients undergoing surgery sometimes become painfully aware of what’s being done to them despite being under the influence of a general anaesthetic, and the ongoing effort to devise a way to detect whether a patient is conscious.
To me, the most interesting part of the article is the final section, which discusses Giulio Tononi’s theory of consciousness. The remainder of this post is quoted from Joshua Lang’s article.
At the heart of Tononi’s work is his integrated-information theory, which is based on two distinct principles, as intuitive as they are scientific. First, consciousness is informative. Every waking moment of your life provides a nearly infinite reservoir of possible experiences, each one different from the next. Second, consciousness is integrated: you can’t process this information in parts. When you see a red ball, you can’t experience the color red separately from the shape of the ball. When you hear a word, you can’t experience the sound of it separately from its meaning. According to this theory, a more conscious brain is both more informative (it has a deeper reservoir of experiences and stimuli) and more integrated (its perception of these experiences is more unified) than a less conscious one.
Compare the brain to New York City: just as cars navigate the city’s neighborhoods via a patchwork of streets, bridges, tunnels, and highways, electrical signals traverse the brain via a meshwork of neurons. Tononi’s theory predicts that in a fully conscious brain, traffic in one neighborhood will affect traffic in other neighborhoods, but that as consciousness fades—for instance, during sleep or anesthesia—this ripple effect will decrease or disappear.
In 2008, in one of several experiments demonstrating this effect, Tononi pulsed the brains of 10 fully conscious subjects with his electromagnetic gun—the equivalent of, say, injecting a flood of new cars into SoHo. The traffic (the electromagnetic waves) rippled across Manhattan (the brain): things jammed up in Tribeca and Greenwich Village, even in Chelsea. Tononi’s EEG electrodes captured ripples and reverberations that were different for every subject and for every region of the brain, patterns as complex and varied as the traffic in Manhattan on any given day.
Tononi then put the same subjects under anesthesia. Before he pulsed his gun again, the subjects’ brain traffic seemed as busy as when they were conscious: cars still circulated in SoHo and Tribeca, in Greenwich Village and Chelsea. But the pulse had a drastically different effect: This time, the traffic jam was confined to SoHo. No more ripples. “It’s as if [the brain] has fragmented into pieces,” Tononi told me. He published these findings in 2010, and also used them to file a patent for “a method for assessing anesthetization.”
Tononi is to his neuroscientist peers as the 18th-century philosopher Immanuel Kant was to his empiricist counterpart David Hume. Like most modern neuroscientists, Hume saw only the “easy problem.” He proposed that consciousness was nothing more and nothing less than the bundling of various bits of experiential knowledge, or, as he called them, “perceptions.” Using this logic, my physiological argument against free will could stand.
Kant, however, believed that the mind is more than an accumulation of experiences of the physical world. Like Descartes 150 years earlier and David Chalmers 200 years later, Kant focused on the “hard problem,” making the logical argument that something beyond sensory inputs must account for the subjectivity of conscious experience—what Kant called “transcendental” consciousness. Tononi’s theory hinges on a similar conception of consciousness as something more than the sum of its experiential parts—leaving room, then, for the possibility of free will.
The amount of integrated information in the brain—the quantity of consciousness—is what Tononi calls phi. He believes he can approximate it with a combination of his TMS‑EEG technology and mathematical models. Many well-known philosophers and neuroscientists, however, remain skeptical. Chalmers has praised Tononi for his bold attempt to quantify consciousness, but he doesn’t think Tononi has come any closer to solving the hard problem. And even Tononi admits that, in scientific-research time, his theory is still in its infancy. What Tononi has made progress on is neither the easy nor the hard problem: it’s the practical problem. He is currently developing a machine that has the potential to end anesthesia awareness once and for all. Like the BIS monitor, the device would provide a numerical assessment of a patient’s awareness, and would be simple and compact enough to become a regular fixture in operating rooms. Unlike the BIS monitor, it would also be relevant outside the operating room. Whereas the BIS is rooted in data specific to surgery, Tononi has developed a comprehensive theory of consciousness that could, with appropriate technological tweaks, be applied in any number of medical, scientific, or social settings.
While subduing consciousness is the most urgent aspect of Tononi’s work, he is especially animated when discussing consciousness in its fullest, brightest state. In his office in Madison, he described a hypothetical device called a “qualiascope” that could visualize consciousness the same way telescopes visualize light waves, or thermal goggles visualize heat. The more integrated the information—that is, the more conscious the brain—the brighter the qualiascope would glow. Using the device in an operating room, you would watch a patient’s consciousness fade to a dull pulse. If he woke up mid-operation, you might see a flicker.
But if you turned your gaze away from the operating room, you would gain an astonishing perspective on the universe. “The galaxy would look like dust,” Tononi told me. “Within this empty, dusty universe, there would be true stars. And guess what? These stars would be every living consciousness. It’s really true. It’s not just a poetic image. The big things, like the sun, would be nothing compared to what we have.”