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Philosophical Transactions of the Royal... Aug 1997A brain-damaged patient (D.F.) with visual form agnosia is described and discussed. D.F. has a profound inability to recognize objects, places and people, in large part...
A brain-damaged patient (D.F.) with visual form agnosia is described and discussed. D.F. has a profound inability to recognize objects, places and people, in large part because of her inability to make perceptual discriminations of size, shape or orientation, despite having good visual acuity. Yet she is able to perform skilled actions that depend on that very same size, shape and orientation information that is missing from her perceptual awareness. It is suggested that her intact vision can best be understood within the framework of a dual processing model, according to which there are two cortical processing streams operating on different coding principles, for perception and for action, respectively. These may be expected to have different degrees of dependence on top-down information. One possibility is that D.F.'s lack of explicit awareness of the visual cues that guide her behaviour may result from her having to rely on a processing system which is not knowledge-based in a broad sense. Conversely, it may be that the perceptual system can provide conscious awareness of its products in normal individuals by virtue of the fact that it does interact with a stored base of visual knowledge.
Topics: Adult; Agnosia; Carbon Monoxide Poisoning; Cognition; Female; Humans; Magnetic Resonance Imaging; Occipital Lobe; Pattern Recognition, Visual; Temporal Lobe; Tomography, Emission-Computed; Vision Disorders; Visual Perception
PubMed: 9304691
DOI: 10.1098/rstb.1997.0107 -
Cognitive Neuropsychology 2012Developmental prosopagnosia (DP) is defined by severe face recognition problems resulting from a failure to develop the necessary visual mechanisms for processing faces.... (Review)
Review
Developmental prosopagnosia (DP) is defined by severe face recognition problems resulting from a failure to develop the necessary visual mechanisms for processing faces. While there is a growing literature on DP in adults, little has been done to study this disorder in children. The profound impact of abnormal face perception on social functioning and the general lack of awareness of childhood DP can result in severe social and psychological consequences for children. This review discusses possible aetiologies of DP and summarizes the few cases of childhood DP that have been reported. It also outlines key objectives for the growth of this emerging research area and special considerations for studying DP in children. With clear goals and concerted efforts, the study of DP in childhood will be an exciting avenue for enhancing our understanding of normal and abnormal face perception for all age groups.
Topics: Child; Child, Preschool; Female; Humans; Male; Pattern Recognition, Visual; Prosopagnosia; Recognition, Psychology; Research; Visual Perception
PubMed: 23140142
DOI: 10.1080/02643294.2012.722547 -
Cortex; a Journal Devoted To the Study... Mar 1992The case is presented of a patient who showed visual naming disturbances caused by a left occipital infarction. His performance on tests of visual naming, of recognition... (Review)
Review
The case is presented of a patient who showed visual naming disturbances caused by a left occipital infarction. His performance on tests of visual naming, of recognition not requiring a verbal response, and of verbal-visual matching demonstrated a wide range of qualitatively different errors, including complete inability to recognize the object, access to partial semantic knowledge, and mere name finding difficulty. On the basis of the present case and of a review of the recent literature, the clinical distinction between visual associative agnosia and optic aphasia and the relation of these disorders with the anatomical site of lesion are discussed.
Topics: Agnosia; Anomia; Aphasia; Brain Mapping; Cerebral Infarction; Dominance, Cerebral; Hemianopsia; Humans; Limbic System; Male; Mental Recall; Middle Aged; Neuropsychological Tests; Occipital Lobe; Pattern Recognition, Visual; Psychomotor Performance; Tomography, X-Ray Computed; Visual Pathways
PubMed: 1374001
DOI: 10.1016/s0010-9452(13)80163-3 -
Current Neurology and Neuroscience... Mar 2017The current review integrates recent findings regarding the construct of self-awareness in dementia from both clinical and cognitive perspectives. We present the... (Review)
Review
The current review integrates recent findings regarding the construct of self-awareness in dementia from both clinical and cognitive perspectives. We present the predominant theoretical models of awareness and summarize both traditional and emerging approaches to assessing awareness from clinical and meta-cognitive perspectives. In this review, we focus primarily on findings from recent studies in anosognosia and meta-cognition in the context of neurodegenerative disease with special emphasis on Alzheimer's disease and frontotemporal dementia. Emerging trends in the study of awareness, including examination of the longitudinal course of anosognosia, and investigation of the neural substrates underlying meta-cognitive abilities are addressed. Finally, the practical importance of studying and assessing awareness from both theoretical and clinical angles is emphasized.
Topics: Aged; Agnosia; Alzheimer Disease; Awareness; Frontotemporal Dementia; Humans; Metacognition; Models, Psychological; Neuropsychological Tests
PubMed: 28283961
DOI: 10.1007/s11910-017-0734-1 -
International Journal of Molecular... Apr 2021Deficits in olfaction and taste are among the most frequent non-motor manifestations in Parkinson's disease (PD) that start very early and frequently precede the PD... (Review)
Review
Deficits in olfaction and taste are among the most frequent non-motor manifestations in Parkinson's disease (PD) that start very early and frequently precede the PD motor symptoms. The limited data available suggest that the basis of the olfactory and gustatory dysfunction related to PD are likely multifactorial and may include the same determinants responsible for other non-motor symptoms of PD. This review describes the most relevant molecular and genetic factors involved in the PD-related smell and taste impairments, and their associations with the microbiota, which also may represent risk factors associated with the disease.
Topics: Agnosia; Biomarkers; Disease Susceptibility; Genetic Predisposition to Disease; Genetic Variation; Humans; Microbiota; Models, Biological; Olfactory Perception; Parkinson Disease; Taste Perception
PubMed: 33924222
DOI: 10.3390/ijms22084286 -
Journal of the Neurological Sciences Dec 2022Vestibular Agnosia - where peripheral vestibular activation triggers the usual reflex nystagmus response but with attenuated or no self-motion perception - is found in...
Vestibular Agnosia - where peripheral vestibular activation triggers the usual reflex nystagmus response but with attenuated or no self-motion perception - is found in brain disease with disrupted cortical network functioning, e.g. traumatic brain injury (TBI) or neurodegeneration (Parkinson's Disease). Patients with acute focal hemispheric lesions (e.g. stroke) do not manifest vestibular agnosia. Thus, brain network mapping techniques, e.g. resting state functional MRI (rsfMRI), are needed to interrogate functional brain networks mediating vestibular agnosia. Hence, we prospectively recruited 39 acute TBI patients with preserved peripheral vestibular function and obtained self-motion perceptual thresholds during passive yaw rotations in the dark and additionally acquired whole-brain rsfMRI in the acute phase. Following quality-control checks, 26 patient scans were analyzed. Using self-motion perceptual thresholds from a matched healthy control group, 11 acute TBI patients were classified as having vestibular agnosia versus 15 with normal self-motion perception thresholds. Using independent component analysis on the rsfMRI data, we found altered functional connectivity in bilateral lingual gyrus and temporo-occipital fusiform cortex in the vestibular agnosia patients. Moreover, regions of interest analyses showed both inter-hemispheric and intra-hemispheric network disruption in vestibular agnosia. In conclusion, our results show that vestibular agnosia is mediated by bilateral anterior and posterior network dysfunction and reveal the distributed brain mechanisms mediating vestibular self-motion perception.
Topics: Humans; Vestibule, Labyrinth; Brain; Brain Mapping; Magnetic Resonance Imaging; Brain Injuries; Sensation; Agnosia
PubMed: 36332321
DOI: 10.1016/j.jns.2022.120458 -
Philosophical Transactions of the Royal... Feb 2011We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms... (Review)
Review
We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms (intuitively related to remapping impairments) are observed in both neglect and constructional apraxia. More specifically, we review findings from the intervening saccade paradigm in humans--and present additional original data--which suggest a specific role of the asymmetrical network at the temporo-parietal junction (TPJ) in the right hemisphere in visual remapping: following damage to the right dorsal posterior parietal cortex (PPC) as well as part of the corpus callosum connecting the PPC to the frontal lobes, patient OK in a double-step saccadic task exhibited an impairment when the second saccade had to be directed rightward. This singular and lateralized deficit cannot result solely from the patient's cortical lesion and, therefore, we propose that it is due to his callosal lesion that may specifically interrupt the interhemispheric transfer of information necessary to execute accurate rightward saccades towards a remapped target location. This suggests a specialized right-hemispheric network for visuo-spatial remapping that subsequently transfers target location information to downstream planning regions, which are symmetrically organized.
Topics: Agnosia; Animals; Apraxias; Haplorhini; Humans; Parietal Lobe; Saccades; Space Perception; Visual Perception
PubMed: 21242144
DOI: 10.1098/rstb.2010.0258 -
European Neurology 2009Music, as language, is a universal and specific trait to humans; it is a complex ability with characteristics that are unique compared to other cognitive abilities.... (Review)
Review
Music, as language, is a universal and specific trait to humans; it is a complex ability with characteristics that are unique compared to other cognitive abilities. Nevertheless, several issues are still open to debate, such as, for example, whether music is a faculty that is independent from the rest of the cognitive system, and whether musical skills are mediated by a single mechanism or by a combination of processes that are independent from one another. Moreover, the anatomical correlations of music have yet to be clarified. The goal of this review is to illustrate the current condition of the neuropsychology of music and to describe different approaches to the study of the musical functions. Hereby, we will describe the neuropsychological findings, suggesting that music is a special function carried out by different and dedicated processes that are probably subserved by different anatomical regions of the brain. Moreover, we will review the evidence obtained by working with brain-damaged patients suffering from music agnosia, a selective impairment in music recognition.
Topics: Agnosia; Brain; Creativity; Functional Laterality; Humans; Models, Psychological; Music; Music Therapy; Neuropsychological Tests
PubMed: 19295213
DOI: 10.1159/000206851 -
Vision Research May 2015Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when...
Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when asked to open her thumb and forefinger a matching amount. Remarkably, however, DF adjusts her hand aperture to accommodate the width of objects when reaching out to pick them up (grip scaling). While this spared ability to grasp objects is presumed to be mediated by visuomotor modules in her relatively intact dorsal stream, it is possible that it may rely abnormally on online visual or haptic feedback. We report here that DF's grip scaling remained intact when her vision was completely suppressed during grasp movements, and it still dissociated sharply from her poor perceptual estimates of target size. We then tested whether providing trial-by-trial haptic feedback after making such perceptual estimates might improve DF's performance, but found that they remained significantly impaired. In a final experiment, we re-examined whether DF's grip scaling depends on receiving veridical haptic feedback during grasping. In one condition, the haptic feedback was identical to the visual targets. In a second condition, the haptic feedback was of a constant intermediate width while the visual target varied trial by trial. Despite this incongruent feedback, DF still scaled her grip aperture to the visual widths of the target blocks, showing only normal adaptation to the false haptically-experienced width. Taken together, these results strengthen the view that DF's spared grasping relies on a normal mode of dorsal-stream functioning, based chiefly on visual feedforward processing.
Topics: Aged; Agnosia; Analysis of Variance; Carbon Monoxide Poisoning; Feedback, Sensory; Female; Hand; Humans; Male; Middle Aged; Movement; Psychomotor Performance; Vision Disorders; Visual Perception
PubMed: 25199609
DOI: 10.1016/j.visres.2014.08.016 -
Proceedings of the National Academy of... Feb 1998Studies of patients with focal brain damage suggest that topographical representation is subserved by dissociable neural subcomponents. This article offers a condensed... (Review)
Review
Studies of patients with focal brain damage suggest that topographical representation is subserved by dissociable neural subcomponents. This article offers a condensed review of the literature of "topographical disorientation" and describes several functional MRI studies designed to test hypotheses generated by that review. Three hypotheses are considered: (i) The parahippocampal cortex is critically involved in the acquisition of exocentric spatial information in humans; (ii) separable, posterior, dorsal, and ventral cortical regions subserve the perception and long term representation of position and identity, respectively, of landmarks; and (iii) there is a distinct area of the ventral occipitotemporal cortex that responds maximally to building stimuli and may play a role in the perception of salient landmarks. We conclude with a discussion of the inferential limitations of neuroimaging and lesion studies. It is proposed that combining these two approaches allows for inferences regarding the computational involvement of a neuroanatomical substrate in a given cognitive process although neither method can strictly support this conclusion alone.
Topics: Agnosia; Animals; Brain; Brain Mapping; Head Injuries, Closed; Humans; Magnetic Resonance Imaging; Maze Learning; Models, Neurological; Space Perception; Temporal Lobe
PubMed: 9448249
DOI: 10.1073/pnas.95.3.839