People affected by aphantasia still have a mental image pattern, even when they can not consciously “see” it. An international team of scientists, including researchers from UNSW Sydney, used a style of MRI brain scanning to learn more about neural processes in people affected by aphantasia. They found that when people with aphantasia attempt to recall a picture in the imagination, the primary visual cortex – the a part of the brain that processes image-like visual information – is activated, but any images that arise remain unconscious to the individual.
Journal/conference: Current biology
Tests: Paper
Organization(s): University of New South Wales, South China Normal University
Founder: This work was supported by the Ministry of Science and Technology of China (2021ZD0204200), the China-Germany Research Promotion Center (M-0705), the National Natural Science Foundation of China (32371100), the Guangdong Natural Science Foundation (2023A1515012596), and the Australian Research Council Scientific grants are awarded DP220100183 and FT220100388.
Media publication
WITH: University of New South Wales
Research has shown that the a part of the brain that processes image-like visual information is wired in another way in people affected by aphantasia, a condition during which people cannot voluntarily generate visual mental images.
An international team of scientists, including researchers from UNSW Sydney, used a style of MRI brain scanning to learn more about neural processes in people affected by aphantasia.
They found that when an individual affected by aphantasia tries to recall a picture in the imagination, the primary visual cortex – the a part of the brain that processes image-like visual information – is activated, but any images that arise remain unconscious to the individual.
Published today, the study, led by scientists from UNSW and South China Normal University, used a spread of techniques to measure brain activity. Their findings challenge the existing theory that activity in the primary visual cortex directly produces conscious visual images.
“People suffering from aphantasia do appear to have certain kinds of images, but they remain too faint or distorted to become conscious or to be measured by our standard measurement techniques,” says Prof. Joel Pearson, co-author of the study conducted at UNSW University School of Psychology. “This may be because the visual cortex is wired differently, as evidenced by data from the new study. This research not only deepens our understanding of the brain, but also pushes the boundaries of our thinking about imagination and consciousness.”
What can we learn about aphantasia?
Aphantasia has been verified in previous studies using sensory means – for instance, through changes in skin conductance in response to emotional storiesand no pupil response to brilliant images.
“If you try to imagine a beach, you will probably ‘see’ it in your mind’s eye,” says Prof. Pearson. “People suffering from aphantasia don’t have this image in their mind – it’s just blank.”
AND study 2020, Future Minds Lab of prof. Pearson at UNSW found that individuals affected by aphantasia reported a reduced ability to recollect the past, imagine the future and even dream.
Although there may be physiological evidence for aphantasia, little is thought about the underlying neural mechanisms of the disease.
Existing research, Doctorates in psychology and neuroscience have shown that visual experiences are closely linked to neural activity in the early visual areas of the brain – the part that processes visual stimuli at the earliest stages. The primary visual cortex is especially necessary since it processes visual information in the type of images during perception and formation of mental images, and its activation strength and size are related to each vividness and power of imagined content.
Previous research they even deciphered and reconstructed visual images based on neural activity in these areas, highlighting their role in creating subjective visual experiences. However, until now it was unclear whether people affected by aphantasia had this sort of neural activity in the primary visual cortex.
Using magnetic resonance imaging to review brain activity
Two cohorts took part in the study – 14 people with aphantasia and 18 people from the control group with typical imagination.
Participants underwent two different tests to evaluate their visual images, followed by functional MRI (fMRI) scans. The scans used blood oxygen level-dependent (BOLD) fMRI, a way for measuring brain activity by detecting changes in blood oxygenation.
During the scans, participants viewed or imagined colourful striped patterns that selectively activated the primary visual cortex. BOLD signals were recorded during passive perception or attempts to assume these patterns.
Challenging traditional results
Analysis of the results showed that participants with aphantasia showed a reduced BOLD response during perception in comparison with the control group.
Although people with aphasia reported little or no conscious imagery, clear neural patterns were still generated during the imaging trials, and the team even managed to make use of algorithms to “decode” what people with aphthasia were attempting to imagine based on brain activity in the original stage. visual cortex. This suggests that there may be indeed an image-specific representation in the brain, it just stays unconscious. These neural patterns are fundamentally different from perception and from the patterns of individuals with mental images.
“Our results show that when a person with aphantasia tries to imagine, their brain continues to create a representation in the early visual cortex. It’s as if the brain carries out calculations but skips the last step, which is to show the result on the screen,” says Prof. Pearson: “What this tells us is that mental imagery isn’t just about the brain ‘lighting up’ – it’s about how that activity is transformed into something we can actually experience.”
Bridging the gap between the visible and the invisible
Aphantasia is a relatively new area of research and there is still much unknown.
“This study bridges the gap between the visible and the invisible. “It is incredible that people suffering from aphantasia still have the neural pattern of image formation, even if they cannot consciously ‘see’ it,” says Prof. Pearson.
These findings have broader implications for understanding how the brain generates conscious experiences and may help develop clinical strategies for conditions involving altered mental images.
“We want and need to learn more about how mental imagery plays a key role in many psychological therapies and how strong imagery is associated with disorders such as schizophrenia and Parkinson’s disease,” says Prof. Pearson. “Understanding the neurological basis of aphantasia could have major implications for a range of disorders and treatments that potentially enable people with aphantasia to engage in mental imagery.”
Although this study breaks recent ground in our understanding of aphantasia, further research, including studies with larger samples, continues to be needed.
“We next plan to seek out out why exactly these representations in the visual brain don’t produce conscious images in people with aphantasia,” says Prof. Pearson.
