The brains of people with aphantasia may have unusual wiring, according to new research. The study suggests that in people with the condition – which involves having no “mind’s eye”, or an inability to conjure up mental images – the brain’s visual cortex is still active and producing visual information. The only trouble is, these images can’t be consciously perceived.
Aphantasia is one of these things that can only truly be understood by people who experience it. For people who are able to imagine what things look like as easily as breathing, it’s hard to conceptualize having no mind’s eye.
“If you try and imagine a beach, you can probably ‘see’ it in your mind’s eye. People with aphantasia don’t get that mental picture – it’s just blank,” explained co-author Professor Joel Pearson from the University of New South Wales Sydney in a statement.
The term “aphantasia” was only coined in 2015, giving a scientific label to an experience that many with the condition were completely unaware was rare or unusual. Early work by University of Exeter neurologist Professor Adam Zeman opened up a whole new world of research, as neuroscientists sought to try and understand what made the brains of people with aphantasia different, and how it might affect other aspects of cognition.
This latest study recruited 14 people with aphantasia and an 18-strong control group. Both groups underwent tests of visual imagery before having a functional magnetic resonance imaging (fMRI) scan of their brains. While in the scanner, they were asked to either look at or imagine colored stripy patterns. The fMRI measures changes in blood oxygen levels that indicate increased activity in different parts of the brain.
Analysis showed that those with aphantasia had a reduced brain activity signal while they were just looking at the stripes compared with the control group.
When asked to imagine patterns, the brains of people with aphantasia were active in the visual cortex, as we would typically expect. The scientists were even able to “decode” these activity patterns to get an idea of what images they were trying to imagine. But, crucially, the participants themselves still only “saw” a blank slate in their minds.
“Our results show that when someone with aphantasia tries to imagine, their brains still seem to create a representation in the early visual cortex. It’s like their brain is doing the math but skipping the final step of showing the result on a screen,” said Professor Pearson.
“This tells us that mental imagery isn’t just about the brain ‘lighting up’ – it’s about how that activity is formatted into something we can actually experience.”
There’s still so much we don’t understand about aphantasia. It’s not just a quirk that some people have – the underlying neurobiology could have links to a range of different brain conditions and can help us learn fundamental things about how our brains generate imagery.
“We want and need to know more about how mental imagery is central to many psychological therapies and how superstrong imagery is associated with disorders such as schizophrenia and Parkinson’s disease,” said Professor Pearson, which is why further work with larger sample sizes is now needed.
“This research bridges the gap between the seen and the unseen,” Professor Pearson added. “It’s incredible to think that people with aphantasia still have a neural blueprint for imagery, even if they can’t consciously ‘see’ it.”
The study is published in the journal Current Biology.
Source Link: Aphantasia: What’s Happening In The Brains Of People Who Have No Mind’s Eye?
