Visual agnosia

BACKGROUND: Acquired color anomalies caused by cerebral trauma are classified as either achromatopsias or dyschromatopsias (Zeki, Brain 113:1721-1777, 1990). The three main brain regions stimulated by color are V1, the lingual gyrus, which was designated as human V4 (hV4), and the fusiform gyrus, designated as V4α. (Zeki, Brain 113:1721-1777, 1990). An acquired cerebral color anomaly is often accompanied by visual field loss (hemi- and quadrantanopia), facial agnosia, prosopagnosia, visual agnosia, and anosognosia depending on the underlying pathology (Bartels and Zeki, Eur J Neurosci 12:172-193, 2000), (Meadows, Brain 97:615-632, 1974), (Pearman et al...

The sagittal stratum (SS) is a large sheet-like structure where major axonal fiber tracts cross, though its anatomical delineations are still debated. Here we investigated the poorly studied anatomo-functional organization of the right SS using direct electrical stimulation (DES) in patients undergoing wide-awake surgery for a cerebral glioma. Seventeen patients were included. There were six males, the mean age was 38 years old. One patient underwent surgery twice. Fourteen patients were right-handed and one was ambidextrous...

We investigated auditory processing in a young patient who experienced a single embolus causing an infarct in the right middle cerebral artery territory. This led to damage to auditory cortex including planum temporale that spared medial Heschl's gyrus, and included damage to the posterior insula and inferior parietal lobule. She reported chronic difficulties with segregating speech from noise and segregating elements of music. Clinical tests showed no evidence for abnormal cochlear function. Follow-up tests confirmed difficulties with auditory segregation in her left ear that spanned multiple domains, including words-in-noise and music streaming...

Nonconvulsive status epilepticus with neuropsychological symptoms other than aphasia or amnesia is rare. We report two such cases. Case 1, a 62-year-old man with a history of a subcortical hemorrhage in the right lateral temporal lobe and a brain infarct in the left medial temporo-occipital lobes, suddenly developed left unilateral spatial neglect and visual object agnosia. Diffusion-weighted imaging indicated status epilepticus, not stroke. His deficits resolved immediately after treatment with diazepam and phenytoin sodium...

We report a patient with asymmetric Bálint's syndrome (predominantly right-sided oculomotor apraxia and simultanagnosia and optic ataxia for the right hemispace), and multimodal agnosia (apperceptive visual agnosia and bilateral associative tactile agnosia) with accompanying right hemianopia, bilateral agraphesthesia, hemispatial neglect, global alexia with unavailable kinesthetic reading, and lexical agraphia for kanji (Japanese morphograms), after hemorrhage in the left parieto-occipito-temporal area. The coexistence of tactile agnosia, bilateral agraphesthesia, and ineffective kinesthetic reading suggests that tactile-kinesthetic information can be interrupted because of damage to the fiber connection from the parietal lobe to the occipito-temporal area, leading to these tactually related cognitive impairments...

The size-weight illusion is a perceptual illusion where smaller objects are judged as heavier than equally weighted larger objects. A previous informal report suggests that visual form agnosic patient DF does not experience the size-weight illusion when vision is the only available cue to object size. We tested this experimentally, comparing the magnitudes of DF's visual, kinesthetic and visual-kinesthetic size-weight illusions to those of 28 similarly-aged controls. A modified t-test found that DF's visual size-weight illusion was significantly smaller than that of controls (zcc  = -1...

No abstract text is available yet for this article.

Acquired prosopagnosia is usually a consequence of bilateral or right hemisphere lesions and is often associated with topographical disorientation and dyschromatopsia. Left temporo-occipital lesions sometimes result in a face recognition disorder but in a context of visual object agnosia with spared familiarity feelings for faces, usually in left-handers. We describe a patient with a left temporo-occipital hemorrhagic lesion unexpectedly resulting in a deficit of face familiarity, which could represent a mild form of associative prosopagnosia...

Recent findings suggest that both dorsal and ventral visual pathways process shape information. Nevertheless, a lesion to the ventral pathway alone can result in visual agnosia, an impairment in shape perception. Here, we explored the neural basis of shape processing in a patient with visual agnosia following a circumscribed right hemisphere ventral lesion and evaluated longitudinal changes in the neural profile of shape representations. The results revealed a reduction of shape sensitivity slopes along the patient's right ventral pathway and a similar reduction in the contralesional left ventral pathway...

Organic brain disturbances particularly related to frontal cortex structures and subcortical areas including the basal ganglia may play a role in behavioral disinhibition disorders. Kluver-Bucy syndrome (KBS), which is one of the better knowns of these syndromes, includes hyperorality, visual agnosia, and hypersexuality, has been reported to occur after temporal lobe and amygdala lesions; however, several patients who had focal lesions in areas other than the temporal cortex and amygdala have been reported to present partial KBS symptoms...

BACKGROUND: Numerous studies have shown visuoperceptual/visuospatial deficits in dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Visual texture recognition is also impaired in patients with DLB and AD. Although patients with DLB often exhibit visual misidentifications of objects, there are few studies on the relationships between visual texture recognition and viewpoints for object recognition. OBJECTIVES: The aim of this study was to clarify how viewpoints, textures, and visual cognitive functions affect object recognition and result in visual misidentifications in patients with DLB or AD...

BACKGROUND: Heidenhain variant of Cruetzfeldt Jacob Disease is a rare phenotype of the disease. Early and isolated visual symptoms characterize this particular variant of CJD. Other typical symptoms pertaining to muti-axial neurological involvement usually appear in following weeks to months. Commonly reported visual difficulties in Heidenhain variant are visual dimness, restricted field of vision, agnosias and spatial difficulties. We report here a case of Heidenhain variant that presented with very unusual symptoms of palinopsia and oscillopsia...

Visual recognition deficits are the hallmark symptom of visual agnosia, a neuropsychological disorder typically associated with damage to the visual system. Most research into visual agnosia focuses on characterizing the deficits through detailed behavioral testing, and structural and functional brain scans are used to determine the spatial extent of any cortical damage. Although the hierarchical nature of the visual system leads to clear predictions about the temporal dynamics of cortical deficits, there has been little research on the use of neuroimaging methods with high temporal resolution to characterize the temporal profile of agnosia deficits...

[Background] Supranuclear extraorbital muscle palsy is the core feature of progressive supranuclear palsy (PSP), and ordinarily presents as spontaneous vertical gaze constriction. However, higher visual function associated with visuospatial cognition in PSP patients was not previously considered. [Case presentation] We present a 72-year old right-handed man with PSP- Richardson syndrome (PSP-RS) and abnormal higher visual function. His symptoms began 2 years previously and included the use of small steps while walking, forgetfulness, and postural instability...

The functional and neural organisation of auditory knowledge is relatively poorly understood. The breakdown of conceptual knowledge in semantic dementia has revealed that pre-morbid expertise influences the extent to which knowledge is differentiated. Whether this principle applies to a similar extent in the auditory domain is not yet known. Previous reports of patients with impaired auditory vs. intact visual expert knowledge suggest that expertise may have differential effects upon the organisation of auditory and visual knowledge...

BACKGROUND: Intraventricular schwannoma is extremely rare, with only 35 cases reported to date in the literature. Consequently, its etiology and pathogenesis are still unclear, and thus require further investigations. Here, we report on and discuss a rare case of intraventricular schwannoma to elucidate on this matter. CASE DESCRIPTION: A 26-year-old male patient was admitted to our institution with a one-month history of headaches and left hemianopsia. At diagnosis, magnetic resonance imaging of the brain revealed a well-demarcated mass with surrounding edema in the right lateral ventricle...

Visual perception is humans' preferred way for taking information on the surrounding world. Visual perception is frequently impaired in patients with Alzheimer's disease, lessening patients' quality of life, and making evaluation of other cognitive deficits more complicated. Our review covers the recent literature describing visual perception deficits in patients suffering from Alzheimer's disease by classifying them according to their neuroanatomical correspondence: retina, visual pathway, subcortical structures, occipital visual cortex, occipito-temporal "what" and occipito-parietal "where" pathways...

Importance: The neuronal mechanism of visual agnosia and foveal crowding that underlies the behavioral symptoms of several classic neurodegenerative diseases, including impaired holistic perception, navigation, and reading, is still unclear. A better understanding of this mechanism is expected to lead to better treatment and rehabilitation. Objective: To use state-of-the-art neuroimaging protocols to assess a hypothesis that abnormal population receptive fields (pRF) in the visual cortex underlie high-order visual impairments...

Forward models allow individuals to learn to predict the sensory consequences of their own behavior. Social forward models have been proposed as an extension of forward models, allowing individuals to learn to predict the response of another to the individual's own behavior. This article proposes similarly that an individual who treats their reflection as another may learn to predict the behavior of their reflection, offering a new perspective on mirror self-recognition and a potential framework through which to investigate visual delusions...

Tracing the history of neglect is intriguing, as diverse terminologies have been used to characterize a multi-factorial disorder with rather startling manifestations. In part, heterogeneous terms may have hinted at distinct subtypes. Thus, different variants of hemi-inattention and neglect relate conceptually, but may be functionally dissociable. Patients with neglect, acting as if the world-space they perceive is full, do not phenomenally experience the omissions or absences so patently obvious to an observer...