A new brain-imaging study published in the journal Proceedings of the National Academy of Sciences has shed more insight into a mysterious subject: the communication among brain areas during the state of awareness. The researchers of the study spotted global changes occurring in certain brain areas as they interact with each other – findings that challenge previous hypotheses that were formulated in the past.
The research findings are thought to be extremely promising, as explained by one of the authors of the study:-
“Identifying the fingerprints of consciousness in humans would be a significant advancement for basic and medical research, let alone its philosophical implications on the underpinnings of the human experience,” said René Marois, professor and chair of psychology at Vanderbilt University and senior author of the study. “Many of the cognitive deficits observed in various neurological diseases may ultimately stem from changes in how information is communicated throughout the brain.”
The aim of the researchers was to characterise the way connections between parts of the brain were related to awareness. Theories pertaining to the neural basis of consciousness fall into two groups: focal and global. The former posits that specific regions of the brain generate consciousness while the latter puts forward that large-scale changes in activity, instead of restricted ones, are behind awareness. The researchers meant to find out which one is more in line with truth. They made use of the graph theory to mathematically decipher the interactive links existing among the brain regions concerned.
“With graph theory, one can ask questions about how efficiently the transportation networks in the United States and Europe are connected via transportation hubs like LaGuardia Airport in New York,” Douglass Godwin, graduate student and lead author on the research, said. “We can ask those same questions about brain networks and hubs of neural communication.”
24 participants were made to go through a functional magnetic resonance imaging (fMRI) experiment.
They were asked to identify a disk while in the fMRI scanner; the disk was briefly flashed on a screen. They had to state whether they were able to identify the disk and rate the confidence level with which they gave the answer.
The results of high-confidence trials during which the target was detected (‘aware trials’) were compared with those trials when it was not spotted (‘unaware trials’).
The results generated were particularly different from others obtained from studies where conventional analysis methods were used. Unlike the other results, no area or group of areas were seen to be more connected during awareness of the target. Rather, the whole brain seems to become functionally more connected after the awareness periods.
“We know there are numerous brain networks that control distinct cognitive functions such as attention, language and control, with each node of a network densely interconnected with other nodes of the same network, but not with other networks,” Marois said. “Consciousness appears to break down the modularity of these networks, as we observed a broad increase in functional connectivity between these networks with awareness.”
The black dots correspond to the 264 areas of the cerebral cortex that the researchers probed, and the lines correspond to the increased strength of the functional connections between each of these brain areas when subjects consciously perceive the target. The “hotter” colors are associated with stronger connections. This figure illustrates that awareness of the target corresponds to widespread increase in the strength of functional connections (Credit: Marois / Godwin).
The findings suggest that awareness occurs as a result of a widespread interaction. This might mean that the soul does not reside in one single part of the brain.
“We take for granted how unified our experience of the world is. We don’t experience separate visual and auditory worlds, it’s all integrated into a single conscious experience,” Godwin said. “This widespread cross-network communication makes sense as a mechanism by which consciousness gets integrated into that singular world.”