Understanding Consciousness Through Neuroscience

Thursday - July 6 2023, 09:21 UTC - 1 year ago

The $20 million project COGITATE used a head-to-head trial between the two top theories of consciousness to find that consciousness may emerge from a grid-like interconnection of neurons at the back of the head. Meanwhile, scientists at the Human Brain Project honed in on two neural circuits that catastrophically fail as awareness slips away. Neuroscientists tackle the problem of understanding consciousness using two main methods: scanning healthy patients while consciousness is present and studying what breaks down in the brain when it disappears.

Trying to understand consciousness calls to mind images of pensive philosophers in a thinking pose. Soft rock and freestyle rap with lyrics based on theories of consciousness aren’t exactly on the bingo card.

Yet the tunes galvanized an eager crowd at the 26th Association for the Scientific Study of Consciousness (ASSC 26) meeting in New York, as attendees awaited the results of the scientific face-off of the century: a head-to-head trial that pitted the two top theories of consciousness against each other. It found that consciousness may emerge from a grid-like interconnection of neurons at the back of the head.

Launched in 2019, the $20 million project, COGITATE, sought to explore an age-old question: how does consciousness arise? The "outlandish" project threw the field into a tizzy for its audacity. But it set up a fair fight: the teams collaborated on specific experiment designs, published them online, and pre-registered predicted results based on each of their championed theories. Human brain scan data was then collected from six theory-neutral labs around the world, with the results judged by three experts with no money in the game to see how well the measured results matched predicted ones.

The reigning theory is just a first win. The opposing team—which thinks consciousness stems from the executive frontal parts of the brain—is ready to fight back with a new test design. Meanwhile, as the theorist frenemies duked it out, scientists at the Human Brain Project took a stab at nailing down the neural circuits critical for consciousness—particularly why they’re important. Scanning the brains of completely and partially comatose patients—with the help of reconstructed digital brains along the way—they honed in on two neural circuits that catastrophically fail as awareness slips away.

The results may sound familiar. One circuit is located at the back of the brain, and it struggles to receive and integrate information. The other, in the front and side regions, breaks down in its ability to broadcast signals to the rest of the brain. Without the ability to transmit and integrate signals from multiple sources—both from the environment and from internal computations—the biological framework of consciousness breaks down.

As for the team’s thoughts on the consciousness theory battle? Their results "share similarities" with both theories, they said.

The Nebulous Neural Enigma .

Experimental methods to probe consciousness are as numerous as the word’s definitions. From Plato to Einstein to Newton, consciousness has teased the minds of intellectual greats for centuries. We still don’t have an answer. I know I’m conscious. You’re reading this, so you are too. But when it comes to people in a coma, or those "locked in" due to disease or injury, the question becomes far more difficult. As AI, brain organoids, and early human-animal chimeric tissues become increasingly sophisticated, the race is on to develop a measure, however crude, that could identify a spark of consciousness if it arises.

In very broad strokes, neuroscientists tackle the problem using two main methods. One is to scan volunteers’ brains when they’re conscious—like when they’re shown images or asked to imagine a scene—hoping to pick up on what factors or neural signatures are present when consciousness is present. The other is to understand how the brain works normally and then compare that to how it breaks down when consciousness is wiped away, whether naturally, as in a coma, or artificially, as in deep sedation.