Correlation between right anterior prefrontal cortex and introspection

[luke wilson]

_http://www.newscientist.com/article/dn19471-brains-grey-matter-helps-you-introspect.html#.U3ptu_ldVBk

What happens in our brain when the mind is considering itself? Until now, it has been unclear what happens during a navel-gazing session. Now a team of neuroscientists has shed light on the process by identifying an area of the brain that is larger in more introspective individuals.

Introspection is the act of assessing or thinking about one's own thoughts, decisions and feelings. Stephen Fleming from University College London and his colleagues were interested in how the act of introspection - thought to be a crucial component of consciousness - links to the physiology of the brain.

The team asked 32 volunteers to assess the accuracy of their own decision-making by identifying which screen, out of two they were shown, contained the brightest dot. The test was designed so it was equally hard for all participants.

Decision confidence

The participants were then asked how confident they were about their decision, on a scale of 1 to 6. Individuals with a high level of introspective ability should be more confident after making a correct choice and less confident after a poor decision than people who are less good at self-reflection.

After the perceptual test, the team scanned the participants' brains using functional magnetic resonance imaging to look for links between the individual's introspective ability and their brain structure. They found that people with a high introspective ability had a larger amount of grey matter in the right anterior prefrontal cortex, an area of the brain located just behind the eyes, involved in decision-making.

It is thought that there are different levels of consciousness. Sometimes we are aware of mental processes, like playing the piano, while others may proceed in the absence of consciousness, like driving a car, says Fleming. Thinking about our own thoughts occurs when we are more highly aware of our own consciousness.

Type of awareness

"I am cautious about saying that what we are measuring here is consciousness," he says. "But we might be measuring something that is required for a particular type of conscious awareness."

"The study addresses an intriguing problem," says neuroscientist Alan Cowey from the University of Oxford in the UK. "The results reveal a fascinating correlation between a level of self-awareness and activity in the prefrontal cortex. They do not yet reveal the neural mechanisms that underlie introspection but that will surely follow".

One way to understand how introspective decisions get made in the brain could be to repeat the experiment in an fMRI machine. This would enable researchers to look at changes in brain activity in real time, rather than just looking for correlations between brain structure and an individual's level of self-reflection.

In another study, the ability to introspect is inverse to noticing visual optical illusions

_Brain trades off illusion-spotting and introspection

Those who find optical illusions easy to solve might be less inclined to ask themselves why. It seems the human brain may have a trade-off between processing visual information and introspection.

Chen Song and her colleagues at University College London found last year that people with more grey matter in the primary visual cortex were better at solving visual illusions. The team has now looked for size differences elsewhere in the brain that correlate with variation in the visual cortex.

They used a functional MRI scanner to build a map of the primary visual cortex of 30 volunteers while also capturing a structural image of their brains. Running the images through a computer, Song was surprised to find a relationship between the primary visual cortex and a region at the front of the brain called the anterior prefrontal cortex (aPFC).

"When people have a bigger anterior prefrontal cortex, they have a smaller visual cortex, and vice versa," she says.

Previous research has shown that the size of the aPFC is linked to introspection – individuals with more grey matter in this brain region are better able to assess whether they made the right decision. Song's study suggests that more introspective individuals forego finer aspects of visual perception. The team will now carry out behavioural studies to find out if this is the case.

What could be behind this relationship? "Animal studies have shown that some genes involved in brain development are expressed at differing levels along the anterior-posterior axis of the brain," says Song. Those differences might be most stark when comparing structures at opposite ends of the cortex – such as the aPFC and primary visual cortex.

Elliot Freeman at City University in London agrees that the results are a surprise. "But bigger is not necessarily better in terms of brain power," he says. Despite evidence that a large aPFC might be linked to better introspection, a small aPFC might be beneficial too, Freeman says. "It might be better to have fewer synaptic connections for more focused and coherent decision making."

However, more neurons in the visual cortex might boost resolution in visual processing, Freeman adds. "A brain with more visual volume and less frontal volume might actually work better."

I looked for back-up studies to see if this has been verified or not but the only articles I could find referenced the study by the UCL researchers. Cheng Song is a PHD student.