The anterior prefrontal cortex of the brain appears to be larger in individuals who are good at turning their thoughts inward and reflecting upon their decisions, and is also linked to this process of introspection, researchers led by Prof. Geraint Rees from University College London have found.

In the future, the discovery may help scientists understand how certain brain injuries affect an individual’s ability to reflect upon their own thoughts and actions. With such an understanding, it may eventually be possible to tailor appropriate treatments to patients, such as stroke victims or those with serious brain trauma, who may not even understand their own conditions.

“Take the example of two patients with mental illness—one who is aware of their illness and one who is not,” said one of the study’s authors, Stephen Fleming from University College London. “The first person is likely to take their medication, but the second is less likely. If we understand self-awareness at the neurological level, then perhaps we can also adapt treatments and develop training strategies for these patients.”

The researchers recruited 32 healthy human participants and showed them two screens, each containing six patterned patches. One of the screens, however, contained a single patch that was brighter than all the rest. The researchers asked the participants to identify which screen contained the brighter patch, and then to rate how confident they felt about their final answer. After the experiment, participants’ brains were scanned using magnetic resonance imaging, or MRI.

The researchers designed the task to be difficult, so that participants were never completely sure if their answer was correct. They reasoned that participants who are good at introspection would be confident after making correct decisions about the patch, and less confident when they were incorrect about the patch. By adjusting the task, the researchers ensured all of the participants’ decision-making abilities were on par with each others’—only the participants’ knowledge of their own decision-making abilities differed.

So, although each participant performed equally well at the task, their introspective abilities did vary considerably, the researchers confirmed. By comparing the MRI scans of each participant’s brain, they could then identify a correlation between introspective ability and the structure of a small area of the prefrontal cortex. An individual’s meta-cognitive, or “higher-thinking,” abilities were significantly correlated with the amount of gray matter in the right anterior prefrontal cortex and the structure of neighboring white matter, Rees and his team found.

The new study will be published in the 17 September issue of the journal Science, which is published by AAAS, the nonprofit science society.

More info: American Association for the Advancement of Science news