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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

What This Study Is About

Researchers wanted to see what actually happens inside the brain of someone with aphantasia—the inability to create mental imagery (the ability to "see" pictures in your mind). They compared how the brain processes a real image versus how it tries to "picture" that same image from memory.

How They Studied It

This was a deep-dive "case study" on one 35-year-old man with aphantasia. To see his brain in action, researchers used an EEG—a cap with 64 sensors that records electrical activity (brain waves).
The participant performed two main tasks:
1. Perception: Looking at a real photo of a face.
2. Imagery: Closing his eyes and trying to "see" that face in his mind.
The researchers also gave him a battery of memory and logic tests to see if his aphantasia affected his overall thinking skills.

What They Found

The results showed a "broken link" in the brain's wiring. When looking at a real photo, the participant’s brain worked perfectly normally. However, when he tried to *imagine* the face, things got weird:
  • The Missing Screen: In most people, the brain sends signals to the back of the head (the visual cortex) to "display" a mental image. In this participant, that area stayed totally quiet.
  • The Different Path: Instead of starting in the front of the brain (the "command center"), his imagery process started in the side of the brain (the temporal lobe), which handles language and facts.
  • The Workaround: Despite not seeing pictures, he scored normally on memory tests! He wasn't "seeing" the faces; he was remembering them like a list of data.

What This Might Mean

This suggests that aphantasia isn't a problem with "seeing," but a problem with the brain’s "backwards" wiring. Usually, imagining is like perception in reverse; in this case, the signal simply never reaches the brain's "movie screen."
A note of caution: Because this study only looked at one person, we can’t say for sure if every aphantasic brain works this way. It "suggests" a pattern, but doesn't "prove" it for everyone.

One Interesting Detail

The participant described his memory as a "semantic listing strategy." When asked to remember his mother, he doesn't see her face; instead, he instantly pulls up a detailed mental "file" of facts describing what she looks like!
This summary was generated by AI and may contain errors. Always refer to the original paper for accuracy.