Back to all research

Imageless imagery in aphantasia: decoding non-sensory imagery in aphantasia

DOI: 10.21203/rs.3.rs-3162223/v1
Meng, M., Chang, S., Zhang, X., & Pearson, J. (n.d.). Imageless imagery in aphantasia: decoding non-sensory imagery in aphantasia. doi:10.21203/rs.3.rs-3162223/v1

Abstract

Activity in early visual cortex is thought to tightly couple with conscious experience, including feedback-driven mental imagery. However, the state of mental imagery, what takes its place or how any activity relates to qualia in those with aphantasia (a complete lack of visual imagery) remains unknown. In the current study, univariate (amplitude) and multivariate (decoding) BOLD signals during imagery attempts were recorded in primary visual cortex. Unlike in those with imagery, neural signatures in those with validated aphantasia were ipsilateral and could not be cross-decoded with perceptual representations. Further, perception-induced neural activation was weaker in those with aphantasia compared to controls. Together, these data suggest that an imagery-related representation, but with less or transformed sensory information, exists in the primary visual cortex of those with aphantasia. Our data challenges the classic view that activity in primary visual cortex should result in sensory qualia.

Authors

  • Ming Meng4
  • Shuai Chang4
  • Xinyu Zhang3
  • Joel Pearson28

Understanding Imageless Imagery: A Study on Aphantasia

Overview/Introduction

Aphantasia is a condition where individuals cannot form visual mental images, a phenomenon that has puzzled scientists for years. This study explores how the brain functions in those with aphantasia, focusing on the early visual cortex, which is typically active during visual experiences and mental imagery. The research aims to understand what happens in the brain of someone with aphantasia when they attempt to visualize something.

Methodology

Researchers used functional Magnetic Resonance Imaging (fMRI) to observe brain activity in participants with and without aphantasia. Participants were asked to imagine specific visual patterns while their brain activity was recorded. The study compared the brain's response to actual visual stimuli and attempted imagery, using both univariate (amplitude) and multivariate (decoding) analyses of BOLD signals in the primary visual cortex.

Key Findings

  • Brain Activity Patterns: In individuals with aphantasia, brain activity during imagery attempts was different from those who could visualize. Their neural responses were ipsilateral (same side of the brain) and could not be decoded in the same way as perceptual responses.
  • Weaker Perception-Induced Activation: The brain's response to actual visual stimuli was weaker in those with aphantasia compared to those who could visualize.
  • Imagery Without Sensory Qualia: Despite the lack of conscious visual imagery, specific neural patterns were still present in the brains of those with aphantasia during imagery attempts.

Implications

These findings challenge the traditional view that activity in the primary visual cortex is directly linked to conscious visual experiences. The study suggests that even without visual imagery, the brain still forms some kind of representation, though it may be transformed or lack sensory details. This could mean that the brain's ability to process visual information is more complex and not solely dependent on conscious visual experiences.

Limitations

  • Sample Size and Diversity: The study's findings are based on a limited number of participants, which may not fully represent the diversity of experiences among those with aphantasia.
  • Understanding of Neural Representations: While the study identifies differences in brain activity, it does not fully explain what kind of information is represented in the brains of those with aphantasia during imagery attempts.
This research provides new insights into how the brain processes visual information and challenges existing theories about the relationship between brain activity and conscious visual experiences. Future studies could further explore the nature of these neural representations and their implications for understanding visual consciousness.