Brain trades off illusion-spotting and introspection

 作者:辜徒情     |      日期:2019-03-01 09:01:00
By Jessica Hamzelou 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.” Journal reference: Journal of Neuroscience, DOI: 10.1523/jneurosci.0308-11.2011 More on these topics: