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

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.

What This Study Is About

Researchers wanted to see how the brain of someone with aphantasia—the inability to create mental images—functions compared to typical visualizers. They specifically looked at whether the brain uses different pathways or regions when trying to "see" a face in the mind's eye.

How They Studied It

This was a case study of a 35-year-old man, referred to as A.P., who has had aphantasia since birth. Researchers used an EEG (a cap with sensors that measures electrical activity in the brain) to track his brain waves in real-time. They compared his brain activity during two different tasks: looking at an actual picture of a face (perception) and trying to imagine a face (imagery). They also gave him a battery of standard memory and intelligence tests to ensure his overall cognitive abilities were typical.

What They Found

The study found that while A.P.’s brain reacted normally when looking at real pictures, it behaved differently during the imagery task. In typical visualizers, the brain usually starts the process of "imagining" in the frontal areas (the part of the brain responsible for planning and control) and then activates the visual areas at the back of the head. In A.P., the process started in the temporal lobe (an area linked to memory) and failed to activate the primary visual or parietal areas. Essentially, his brain skipped the "visual" step of the process.

What This Might Mean

These findings suggest that aphantasia isn't necessarily a problem with memory or general intelligence, but rather a specific difference in how the brain's "wiring" handles the retrieval of visual information. It suggests that for some, the brain may try to access the concept of an image through memory centers without successfully triggering the visual machinery needed to actually "see" it. Because this is a study of just one person, more research is needed to see if these same brain patterns exist in others with aphantasia.

One Interesting Detail

Despite being unable to picture a face in his mind, A.P. performed exceptionally well on a "Mental Rotation" test—a task where you have to mentally turn a 3D shape to see if it matches another. This shows that he can solve complex spatial problems even without using visual mental imagery.

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

Abstract

Authors

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

Abstract

Authors

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

Abstract

Authors

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

Abstract

Authors

What This Study Is About

How They Studied It

What They Found

What This Might Mean

One Interesting Detail

What This Study Is About

How They Studied It

What They Found

What This Might Mean

One Interesting Detail

Joel Pearson

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