Where does consciousness come from? Brain scientist closes in on the claustrum

"Crown of Thorns" neurons
A digital 3-D reconstruction shows a handful of neurons that wrap around a mouse’s brain and are connected to a sheet of brain cells known as the claustrum. (Allen Institute for Brain Science)

SAN FRANCISCO — For decades, neuroscientist Christof Koch has been searching for the seat of consciousness — a quest that has taken him deep within the brains of mice, and to the doorstep of the Dalai Lama.

Now the president and chief scientific officer of Seattle’s Allen Institute for Brain Science is closing in on a big part of the answer in a small part of the brain.

The part in question is known as the claustrum, a thin, irregular sheet of neurons that’s found in each hemisphere of the brain, underneath the cortex.

Koch and the late biologist Francis Crick, a co-discoverer of DNA’s double helix structure, took note of the claustrum more than a decade ago — but it’s taken that long for experimental techniques to progress to the point where neuroscientists can literally shed light on how the claustrum and its network of connected neurons work.

“It connects to every point of the cortex, bidirectionally,” Koch said Oct. 27 at the World Conference of Science Journalists in San Francisco. “Crick and I hypothesized that the function of the claustrum is to do something like consciousness. In a sense, it acts like the conductor of the cortical symphony.”

Christof Koch describes claustrum
Christof Koch, chief scientific officer and president of the Allen Institute for Brain Science, describes the sheetlike structure of the claustrum while a slide showing its location is displayed. (GeekWire Photo / Alan Boyle)

Mouse studies have shown that a mere handful of long, branching neurons are connected to the claustrum and project into the cortex like a “crown of thorns,” Koch said.

The Allen Institute has gone so far as to put tiny cameras and microscopes directly into the brains of genetically engineered mice, to track how the claustrum and its neuronal networks light up as the mice go about their business. Koch showed off a video clip with flashes of activity.

“At the same time as the mouse is moving, you’re looking at a living claustrum neuron,” Koch told the audience. “You can see what it does now as it moves around and sniffs and does its thing.”

Does that mean that mice are conscious? Koch says yes. He calls himself a “panpsychist,” and suspects that there’s a spectrum of consciousness rather than a sharp division between humans and other animals.

In Koch’s view, the difference between mice and humans is like the difference between a 1970s-era Atari 2600 video console and an iPhone. Both compute, but an Atari 2600 can’t talk back at you. Siri can.

Now experimenters are trying to turn the claustrum on and off in mice to see what happens, Koch said.

To move from mice to humans, the Allen Institute is making use of computer modeling as well as experiments with living tissue taken from human patients in the course of brain surgery.

Experimenting with brains while humans are using them is highly limited, for obvious ethical reasons. Koch did note one episode in which accidental stimulation of the claustrum put an epilepsy patient into a zombie-like state. When the electrode was turned off, the patient had no memory of the intervening time.

 

Allen Institute president and chief scientific officer Christof Koch speaks to the World Conference of Science Journalists

Posted by Alan Boyle on Friday, October 27, 2017

 
There are likely to be more insights ahead, and more ethical quandaries to deal with, as researchers come closer to developing artificially grown masses of human brain cells in the lab, known as cortical organoids.

“Information theory says yes, this piece of cortex will feel like something,” Koch said. “It may feel very different. Because it doesn’t have an eye and an ear, it’s very unclear what it’s going to be conscious of. But in principle, this thing will experience something. … When you have these cortical organoids, and it gets big enough and complex enough in its electrical activity, we have to start thinking about it: Is this thing in pain?”

Is consciousness merely an emergent phenomenon that arises as the cortex chugs through all the sensory information it’s processing? Koch doesn’t think so, and for evidence, he refers to the lessons he learned from the Dalai Lama over the past several years.

“If you do what Buddhists call pure experience or naked awareness, or content-less experience, you’re conscious,” Koch said. “The meditator is conscious without having any specific content.”

So is consciousness something that transcends the physical realm? On that score, Koch differs with the Dalai Lama. He recalled a recent meeting during which the exiled Tibetan religious leader asked him whether neuroscience could lend support to the concept of reincarnation.

“There are four words you can say: ‘No brain, never mind,’” Koch said. “In other words, there has to be a physical mechanism in order for there to be consciousness. It has to be expressed in something physical. It may be something weird — quarks, it may be granularity of space itself, LIGO — but there has to be some mechanism.”

So how did the Dalai Lama react?

“He just smiled,” Koch said.

For more about Koch and his views on AI, consciousness and the brain, check out our report about his presentation at the GeekWire Summit, Koch’s op-ed article for The Wall Street Journal and his cover story for the November issue of Scientific American.

Geekwire’s Alan Boyle is president of the Council for the Advancement of Science Writing, one of the organizers of the World Conference of Science Journalists.