Where is our human consciousness located? While most of us automatically identify the brain as the headquarters of our awareness, neuroscientists seek a more precise location (and understanding) for this unique if everyday phenomenon. A new study finds that consciousness does not make its home in just one brain region. Instead, researchers say, awareness degrades the brain’s modular function and substitutes an integrated connectivity in which widespread communication arises across areas of the cortex. Consciousness, then, arises from cooperative and not solo brain activity.

Since the beginning of thought, philosophers have wondered where we derive our consciousness, and with the advent of sophisticated imaging technologies, neuroscientists have begun to explore this question in steadily increasing depth. Most recently, a 2014 study suggested that one region of the brain works as an on/off switch for awareness — when researchers electrically stimulated the claustrum of a patient, she instantly became unconscious. While this experiment does not prove consciousness resides in the claustrum, it raised many questions about the function of this unusual brain region: a thin, irregular structure of neurons hidden beneath the surface of the neocortex.

Francis Crick and Christof Koch theorize the claustrum functions as “a conductor coordinating a group of players in the orchestra, the various cortical regions.” Their hypothesis is based on the fact that the claustrum receives input from — and projects back to — almost all regions of the outside layer of the brain, the cortex.

Graphs and Images

For the current study, Vanderbilt University researchers investigated whether one or just a few areas of the brain might produce awareness. To accomplish their work, they used graph theory, a branch of mathematics focused on understanding highly complex, advanced networks, and a simple brain imaging experiment.

The experiment began with participants lying down on the hard bed of an MRI scanner. While researchers observed, participants performed a simple task of detecting a disk as it briefly flashed on the screen before them. After each participant completed a number of trials, the researchers compared all the results. They labeled those tests when participants detected the disk as “aware” and those when they missed the disk as “unaware.”

Upon analysis, the researchers discovered that no one area or network of areas in the brain stood out as particularly active during awareness. In fact, the whole brain appeared to become more connected following each report of awareness. “These results provide compelling evidence that awareness is associated with truly global changes in the brain’s functional connectivity,” wrote the authors.

“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,” Douglass Godwin, one of the authors of the study and a graduate student at Vanderbilt, told KurzweilAI. “This widespread cross-network communication makes sense.”

Source: Godwin D, Barry RL, Marois R. Breakdown of the brain’s functional network modularity with awareness. PNAS. 2015.