August 17, 2019

Understanding the nature of consciousness

Since early childhood, Associate Professor Nao Tsuchiya has questioned the nature of consciousness; what it feels like to be born, or to die. Now, with the help of MASSIVE’s supercomputing facilities, he is seeking the answers.

At Monash University’s Turner Institute for Brain and Mental Health, Tsuchiya is exploring some fundamental neuroscientific questions about the boundary between conscious and unconscious, and what happens in the brain when we slip from one conscious state to the other.

“Surprisingly, much of the stuff that’s happening in the brain is quite unrelated to our conscious experience,” he says. “For example, in dreamless sleep or deep general anaesthesia, you don’t experience much and if anything you don’t remember much, but still your brain is extremely active.”

Part of his research explores the differences between the conscious and unconscious brain in experimental models such as the fruit fly, Drosophila melanogaster. This involves recording neuronal activity in these tiny creatures, which nonetheless have more than 100,000 neurons in their brains.

Recording the activity of each of these individual nerve cell generates a colossal amount of data, which is collated into a form of virtual map of brain activity using the supercomputing facilities at MASSIVE.

Researchers are testing what’s called the  integrated information theory of consciousness, which attempts to tease out what systems have consciousness and if anything what kind of conscious perception they have.

“According to the theory, consciousness is something to do with integration of information, a notion which is gaining empirical support,” Tsuchiya says.

To test this, they’re looking at the brain activity of fruit flies under general anaesthesia, called isoflurane. When applied to humans, isoflurane induces loss of consciousness quite reliably. Using MASSIVE, Tsuchiya’s team is trying to retrieve “shape” of information from the recorded brain activity. Their hypothesis is that the more complex the conscious experience becomes, the more complex and integrated the shape of information becomes. For example, when flies are awake, informational shape should become complex as it should reflect integrated processing of hearing, vision, touch and memory.

But in the unconscious anaesthetised state, that integration doesn’t work the same. He likens the anesthetized brain to three people sitting together in a café, but one person is looking at their phone while the other two are talking.

“Some parts are actually talking, but not all of them are connected and not all of them are jointly generating a unified sensory experience,” he says. “That’s what we are trying to test in the neurons.”