An international study involving Monash physicists has confirmed a new approach to measuring consciousness, potentially changing our understanding of complex neurological problems.
The study published yesterday in Physical Review Research describes how tools from physics and complexity theory were used to determine the level of consciousness in fruit flies.
“This is a major problem in neuroscience, where it is crucial to differentiate between unresponsive vegetative patients and those suffering from a condition in which a patient is aware but cannot move or communicate verbally because of complete paralysis of nearly all voluntary muscles in the body,” said study author Dr. Kavan Modi, from the Monash University School of Physics and Astronomy.
The research team, which includes Dr. Modi, Ph.D. candidate Roberto Muñoz also from the School of Physics and Astronomy, and Monash University Psychology Associate Professor Nao Tsuchiya, has found a way to measure the level of conscious arousal in fruit flies using the complex signals produced by the brain.
“Our technique allows us to distinguish between flies that have been anesthetized and those that have not, by calculating the time-complexity of the signals,” said Dr. Modi.
“The study is significant because it highlights an objective way to measure conscious arousal, based on well-established ideas from complexity theory,” he said.
“It is potentially applicable to humans — and it reflects a growing interest in new theories of consciousness that are experimentally testable.”
The research team studied the brain signals produced by 13 fruit flies both when they were awake and when they were anesthetized. They then analyzed the signals to see how complex they were.
“We found the statistical complexity to be larger when a fly is awake than when the same fly is anesthetized,” Dr. Modi said.
“This is important because it suggests a reliable way to determine the level of conscious arousal by tapping into a small region of the brain, rather than many parts of the brain.
“It also suggests that there is a clear marker of conscious arousal that does not depend on specific external stimuli.”
The researchers concluded that applying a similar analysis to other datasets, in particular, human EEG data could lead to new discoveries regarding the relationship between consciousness and complexity.
Reference: “General anesthesia reduces complexity and temporal asymmetry of the informational structures derived from neural recordings in Drosophila” by Roberto N. Muñoz, Angus Leung, Aidan Zecevik, Felix A. Pollock, Dror Cohen, Bruno van Swinderen, Naotsugu Tsuchiya and Kavan Modiay, 22 May 2020, Physical Review Research.