Research Shows Split Brain Activity Allows You to Listen and Drive
We’ve all had the experience of pulling into the driveway, with no clear memory of the drive.
Now a team of University of Wisconsin-Madison consciousness researchers has used brain imaging to show how the brain allows you to drive a familiar path while concentrating on a radio show: It literally splits the tasks in half, with one part of the brain navigating the drive while the other part concentrates on the broadcast.
Even more intriguing, the two circuits operate independently of one another, showing no integration with the task of the other circuit.
“This temporary split may resemble, to some extent, what happens after epilepsy patients have surgery to disconnect the two hemispheres to relieve seizures. The surgically disconnected brain is able to manage two separate streams of consciousness, one per hemisphere.”
The findings were published in the Proceedings of the National Academy of Sciences. The researchers put 13 healthy male volunteers in a driving simulator while their brains were being imaged via functional magnetic resonance imaging (fMRI).
In one condition, the group had to perform the ‘integrated task’ of listening to a GPS-controlled voice giving complex directions to a simulated destination while driving. In the other condition, they performed the ‘split-task’ of listening to an engaging radiotalk show, entirely unrelated to the act of driving.
As anticipated, and consistent with previous research, listening to the GPS voice or the radio show activated the brain networks known to serve listening, while the act of driving activated the distinct ‘driving’ network. However, the relationship between the driving and listening networks looked completely different: during the integrated GPS-listening task, the two networks were integrated and actively exchanging signals with one another.
In contrast, during driving while listening to the radio show, the integration of information decreased to zero. Remarkably, these two networks were more integrated when subjects were doing absolutely nothing, than they were during task performance.
“An intriguing question is what happens to consciousness when driving while listening in the split condition,’’ Tononi notes. “Is there a single conscious stream, with attention deployed primarily to a dominant task, typically listening, and much less to driving? Or does driving become unconscious, as on autopilot? Or, does a normally integrated conscious stream split into two separate conscious streams that coexist within the same brain, as indicated by studies of patients with an anatomically split brain?”
The study’s lead author is Shuntaro Sasai, a research associate of the UW School of Medicine and Public Health’s Department of Psychiatry. Other members of the team include Melanie Boly and Armand Mensen of the UW departments of psychiatry and neurology.
Date Published: 11/30/2016