Multiple-domain dissociation between impaired visual perception and preserved mental imagery in a patient with bilateral extrastriate lesions

• Published in: Neuropsychologia Vol. 36; no. 3; pp. 239 - 249
• Main Authors: Bartolomeo, Paolo, Bachoud-Lévi, Anne-Catherine, De Gelder, Beatrice, Denes, Gianfranco, Barba, Gianfranco Dalla, Brugières, Pierre, Degos, Jean-Denis
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.1998; Elsevier Science
• Subjects: achromatopsia; Adult and adolescent clinical studies; Aged; agnosia; Agnosia - etiology; Agnosia - pathology; Agnosia - physiopathology; Biological and medical sciences; Cerebrovascular Disorders - complications; Cerebrovascular Disorders - pathology; Cerebrovascular Disorders - physiopathology; Color Perception; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Dyslexia, Acquired - etiology; Dyslexia, Acquired - pathology; Dyslexia, Acquired - physiopathology; Female; Form Perception; Humans; Imagination; Magnetic Resonance Imaging; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Occipital Lobe - pathology; Occipital Lobe - physiopathology; Organic mental disorders. Neuropsychology; prosopagnosia; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; pure alexia; Temporal Lobe - pathology; Temporal Lobe - physiopathology; Visual Perception; pure alexia; prosopagnosia; achromatopsia; agnosia; Human; Mental imagery; Nervous system diseases; Visual cortex; Visual imagery; Perceptual disorder; Vision disorder; Visual agnosia; Bilateral; Achromatopsia; Language disorder; Cerebral disorder; Case study; Eye disease; Central nervous system disease; Female; Alexia; Lesion; Prosopagnosia; Elderly; Dyschromatopsia
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/S0028-3932(97)00103-6

A brain-damaged patient is described whose pattern of performance provides insight into both the functional mechanisms and the neural structures involved in visual mental imagery. The patient became severely agnosic, alexic, achromatopsic and prosopagnosic following bilateral brain lesions in the temporo-occipital cortex. However, her mental imagery for the same visual entities that she could not perceive was perfectly preserved. This clear-cut dissociation held across all the major domains of high-level vision: object recognition, reading, colour and face processing. Our findings, together with other reports on domain-specific dissociations and functional brain imaging studies, provide evidence to support the view that visual perception and visual mental imagery are subserved by independent functional mechanisms, which do not share the same cortical implementation. In particular, our results suggest that mental imagery abilities need not be mediated by early visual cortices.