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Cortical activity involved in perception and imagery of visual stimuli in a subject with aphantasia. An EEG case report

DOI: 10.1080/13554794.2022.2122848
Furman, M., Fleitas-Rumak, P., Lopez-Segura, P., Furman, M., Tafet, G., de Erausquin, G. A., & Ortiz, T. (2022). Cortical activity involved in perception and imagery of visual stimuli in a subject with aphantasia. an eeg case report. Neurocase, 28(4), 344–355. doi:10.1080/13554794.2022.2122848

Abstract

Aphantasia has been described as the inability to voluntarily evoke mental images using the "mind's eye." We studied a congenital aphantasic subject using neuropsychological testsand 64 channel EEG recordings, in order to studycortical activity involved in perception and imagery evaluating event-related potentials(N170, P200, N250). The subject is in the normal range of the neuropsychological tests performed, except for specific imagery tests. The EEG results show that when he evokes the same mental image, he starts the evoking process from left temporal instead of frontal areas, he does not activate occipital visual nor left anterior parietal areas.

Authors

  • Mariano Furman1
  • Pablo Fleitas-Rumak1
  • Pilar Lopez-Segura1
  • Martín Furman1
  • Gustavo Tafet1
  • Gabriel A. de Erausquin1
  • Tomás Ortiz1

Understanding Aphantasia: A Case Study

Overview/Introduction

Aphantasia is a unique condition where individuals cannot voluntarily create mental images, often described as lacking a "mind's eye." This study explores the brain activity of a person with congenital aphantasia using neuropsychological tests and advanced brain imaging techniques. The goal is to understand how their brain processes visual perception and imagery compared to individuals without this condition.

Methodology

  • Participant: A 35-year-old male psychiatrist with congenital aphantasia.
  • Tests Conducted: Neuropsychological assessments and 64-channel EEG recordings.
  • EEG Details: Electrodes were placed on the scalp to measure brain activity during tasks involving visual stimuli and mental imagery.
  • Data Analysis: Focused on event-related potentials (ERPs), which are brain responses to specific sensory, cognitive, or motor events.

Key Findings

  • Neuropsychological Tests: The participant performed normally on most tests but struggled with tasks requiring mental imagery.
  • EEG Results:
  • When attempting to evoke mental images, the participant's brain activity started in the left temporal area, unlike typical patterns that begin in the frontal areas.
  • There was no activation in the occipital visual or left anterior parietal areas, which are usually involved in visual imagery.
  • During visual perception tasks, the participant's brain followed a typical pattern, suggesting that the issue lies specifically in imagery, not perception.

Implications

  • Understanding Aphantasia: This study provides insights into the neurological basis of aphantasia, showing that it involves distinct brain activity patterns during imagery tasks.
  • Potential Applications: These findings could help develop better diagnostic tools and interventions for individuals with aphantasia, enhancing our understanding of how different brains process visual information.

Limitations

  • Single Case Study: The study focuses on a single individual, limiting the generalizability of the findings.
  • Task Variety: Only a neutral face image was used; future studies should include a variety of objects to see if results differ.
  • Repetition Effects: The impact of task repetition on brain activity was not fully explored, which could influence results.
In summary, this study sheds light on the unique brain activity patterns of a person with aphantasia, offering a deeper understanding of how this condition affects mental imagery. Further research with more participants and varied tasks could provide additional insights into this intriguing phenomenon.