A new study found that people with aphantasia—individuals who report experiencing no visual imagery at all—also showed reduced activation of the brain’s visual cortex in response to sounds.
The research – led by the University of Glasgow and published in Current Biology – uncovers new insights into the relationship between visual imagery and multisensory integration in people with ‘blind imagination,’ or aphantasia.
When we look at something, information is transmitted from our eyes to a part of our brain called the visual cortex. Aside from its input from the outside world, called feedforward information, the visual cortex also receives feedback information from other parts of the brain.
This feedback information is crucial to help us contextualize and understand what we’re seeing, but it can also allow us to experience things that are not in the external world, as it happens with visual imagery.
The causes of aphantasia are debated, with evidence showing that it might be caused by a reduction of feedback to the visual system, which is what the researchers investigated in this study.
For the research, blindfolded aphantasic participants listened to auditory scenes. Previous work from the researchers has shown that auditory scenes are not only processed in the auditory cortex but are also represented in the visual areas of the brain in blindfolded and congenitally blind participants.
However, aphantasic participants report a reduced representation of sound content in their visual areas. This pattern of results suggests that feedback signals to the visual system could be weaker in aphantasia, which in turn may be linked to the absence of visual imagery.
Professor Lars Muckli, from the University’s School of Psychology and Neuroscience, said: “Visual imagery comes naturally to me – If I am asked to describe a beautiful landscape I would picture it in my mind and then describe it with my minds-eye. Understanding that subjects with aphantasia are blind to the minds-eye is intriguing to me. Our study helps to uncover that Aphantasia might go along with reduced feedback to the early visual cortex.
“One of the co-authors of the study has aphantasia, and it is fascinating to discuss subjective experiences with him to better understand how they differ.”
The study, ‘Decoding sound content in the early visual cortex of aphantasic participants,’ is published in Current Biology. The study was funded from different sources including the Biotechnology and Biological Sciences Research Council ‘Layer-specific cortical feedback’.
