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The Architect Who Lost the Ability to Imagine: The Cerebral Basis of Visual Imagery

DOI: 10.3390/brainsci10020059
Thorudottir, S., Sigurdardottir, H. M., Rice, G. E., Kerry, S. J., Robotham, R. J., Leff, A. P., & Starrfelt, R. (2020). The architect who lost the ability to imagine: the cerebral basis of visual imagery. Brain Sciences, 10(2), 59. doi:10.3390/brainsci10020059

Abstract

While the loss of mental imagery following brain lesions was first described more than a century ago, the key cerebral areas involved remain elusive. Here we report neuropsychological data from an architect (PL518) who lost his ability for visual imagery following a bilateral posterior cerebral artery (PCA) stroke. We compare his profile to three other patients with bilateral PCA stroke and another architect with a large PCA lesion confined to the right hemisphere. We also compare structural images of their lesions, aiming to delineate cerebral areas selectively lesioned in acquired aphantasia. When comparing the neuropsychological profile and structural magnetic resonance imaging (MRI) for the aphantasic architect PL518 to patients with either a comparable background (an architect) or bilateral PCA lesions, we find: (1) there is a large overlap of cognitive deficits between patients, with the very notable exception of aphantasia which only occurs in PL518, and (2) there is large overlap of the patients’ lesions. The only areas of selective lesion in PL518 is a small patch in the left fusiform gyrus as well as part of the right lingual gyrus. We suggest that these areas, and perhaps in particular the region in the left fusiform gyrus, play an important role in the cerebral network involved in visual imagery.

Authors

  • Sandra Thorudottir2
  • Heida Maria Sigurdardottir2
  • Grace E. Rice1
  • Sheila J. Kerry1
  • Ro J. Robotham1
  • Alex P. Leff2
  • Randi Starrfelt1

Understanding the Loss of Visual Imagination: Insights from a Unique Stroke Case

Overview/Introduction

Visual imagery, the ability to picture things in our mind without seeing them, is a fascinating aspect of human cognition. However, some people lose this ability due to brain injuries, a condition known as acquired aphantasia. This study explores the case of an architect, referred to as PL518, who lost his visual imagery following a stroke. By examining PL518 and comparing him with other stroke patients, researchers aim to identify specific brain areas involved in visual imagery.

Methodology

  • Participants: The study focused on PL518 and compared him to four other stroke patients, including another architect.
  • Tests Conducted:
  • Neuropsychological assessments to evaluate cognitive functions like face and object recognition.
  • A modified Vividness of Visual Imagery Questionnaire (VVIQ) to measure the vividness of mental images.
  • Brain Imaging: Structural MRI scans were used to map and compare brain lesions across participants.

Key Findings

  • Unique Imagery Loss: PL518 was the only participant who reported a complete loss of visual imagery after his stroke, despite having similar cognitive deficits to other patients.
  • Lesion Analysis: The study found that PL518 had specific damage in the left fusiform gyrus and the right lingual gyrus. These areas were not damaged in the same way in other patients who retained their visual imagery.
  • Cognitive Performance: PL518 showed impairments in face recognition but performed normally in object and word recognition tasks.

Implications

  • Brain Areas Involved: The findings suggest that the left fusiform gyrus and right lingual gyrus are crucial for visual imagery. Damage to these areas may disrupt the ability to visualize images mentally.
  • Potential for Rehabilitation: Understanding the specific brain regions involved in visual imagery could lead to targeted therapies for individuals with acquired aphantasia.
  • Broader Understanding: The study contributes to the ongoing debate about how visual imagery and perception are processed in the brain, highlighting the complex interplay between different brain regions.

Limitations

  • Small Sample Size: The study's findings are based on a limited number of participants, which may affect the generalizability of the results.
  • Complexity of Imagery: Visual imagery involves multiple brain processes, and the study primarily focused on specific areas, potentially overlooking other contributing regions.
In conclusion, this research provides valuable insights into the cerebral basis of visual imagery, emphasizing the role of specific brain regions in maintaining this cognitive ability. Understanding these mechanisms can pave the way for better diagnosis and treatment of imagery-related deficits following brain injuries.