Object Agnosia Research Articles

Impact of pre-stroke cognitive decline on rehabilitation effectiveness and cognitive-functional status of patients in the acute period of ischemic stroke

Summary. The aim was to assess the influence of premorbid cognitive deficit on the effectiveness of rehabilitation using VR technologies and cognitive-functional status of patients in the acute period of ischemic stroke based on statistical methodology. Materials and methods: 120 patients diagnosed with ischemic stroke were examined. The IQCODE questionnaire was used to identify the patient’s cognitive decline before and the Pandas and SciPy libraries. Results: all patients had a multifunctional type of cognitive impairment with a predominant decline in the areas of executive function, memory, speech and perception. Patients of the 2nd group had a more pronounced deficit in the areas of constructive praxis, episodic memory, semantic information processing and perception. Assessment of the dynamics of cognitive impairment during therapy revealed a significant improvement in memory loss (p=0, 0034), executive dysfunction (p<0.0001) and attention impairment (p=0.0001) in patients of 1st group and regression cognitive deficit in almost all cognitive areas in patients of 2nd group. Factors impeding rehabilitation in 1st group of patients were attention (r = -0,325) and perceptual disorders (r = -0,425); in 2nd group: semantic aphasia (r = -0,425), constructive apraxia (r = -0,325), speech impairment (r = — 0,375), object agnosia (r = -0,323) and IQCODE (r = -0,395). Conclusion: pre-stroke cognitive impairments are predictors of the development and progression of post-stroke cognitive deficits and reduce the possibilities of rehabilitation and cognitive recovery. The introduction of IQCODE in the diagnosis of cognitive dysfunction in the acute period of ischemic stroke is a useful tool in predicting the course and development of cognitive deficit and studying the prospects of rehabilitation programmes using VR technologies in patients with pre-stroke cognitive impairment.

Проблемы диагностики зрительного гнозиса у детей с задержкой психического развития

The issues of diagnosing visual gnosis connected with the ability to recognize and interpret visual stimuli, which is an essential component of general cognitive function, especially sensitive for children with special needs. The purpose of this research is to contribute to the improvement of diagnostic methods for visual gnosis and, as a result, to provide targeted intervention for children with developmental delays experiencing problems with visual perception. In this work, the following methods were used: a specially designed questionnaire for specialists, sheets from a diagnostic album with images of real objects, unfinished images of objects and noisy images; Poppelreiter's test, “Conflicting images”; “Undersized images” (A.F. Anufriev and S.N. Kostromina), as well as the Bourdon–Wiersma test. The study sample consists of 10 specialists (6 psychologists and 4 speech pathologists) and 30 preschool children (5–7 years old) with normotypic development and with special needs. The results of visual gnosis assessment with classical stimulus materials among normotypic children and children with special needs show that a number of stimulus materials are mistakenly interpreted by children and create the illusion of agnosia. To overcome these difficulties, an updated diagnostic stimulus material has been developed, the use of which has shown high effectiveness in assessing visual gnosis in preschool children. The use of updated stimulus material allows the specialist to quickly and accurately diagnose various types of object agnosia, in particular, the agnosia of letters and shapes, optical-spatial, simultaneous and color. As a result with updated stimulus material the specialist has improved accuracy and quality of diagnostic results; the possibility of earlier detection and correction of visual gnosis issues; increased convenience and accessibility of the technique for specialists.

Abnormality of the pulvinar in posterior cortical atrophy: A multimodal MRI study

AbstractBackgroundAlthough the pulvinar is known for its extensive connections with both ventral and dorsal visual streams, details of pulvinar functional connectivity in the setting of posterior cortical atrophy (PCA) remain unclearTo study pulvinar functional connectivity and relevant associations with higher visual dysfunction in PCA.MethodA total of 29 patients with PCA and 30 normal controls were recruited. Each participant underwent comprehensive neuropsychological assessment and both structural and resting‐state functional MRI scanning. Voxel‐based morphometry (VBM) and seed‐based functional connectivity analyses were conducted to assess pulvinar gray matter volume as well as connectivity between the pulvinar and whole brain regions. A partial correlation analysis was performed to analyze neuropsychological test and pulvinar imaging data.ResultCognitive and visual functions including visuospatial processing, visual perception, episodic memory, and naming were impaired among PCA patients. Marked pulvinar atrophy was noted in PCA patients. Furthermore, functional connectivity between the pulvinar and precuneus was significantly decreased in PCA patients as compared to normal controls (FWE corrected; P<0.001). Left pulvinar gray matter volume was found to associate with object agnosia (r = 0.42, P<0.05) and right–left disorientation (r = 0.29, P<0.05) among PCA patients. The bilateral pulvinar region was found to associate with Boston Naming Test (left, r = 0.51, P = 0.015; right, r = 0.46, P = 0.03) and Activities of Daily Living (left, r = ‐0.46, P = 0.019; right, r = ‐0.53, P = 0.006) scores. Correlation analyses did not reveal significant findings concerning functional connectivity.ConclusionOur findings confirm pulvinar degeneration and its contributions in the setting of PCA.

The rehabilitation of object agnosia and prosopagnosia: A systematic review.

Agnosia for objects is often overlooked in neuropsychology, especially with respect to rehabilitation. Prosopagnosia has been studied more extensively, yet there have been few attempts at training it. The lack of training protocols may partially be accounted for by their relatively low incidence and specificity to sensory modality. However, finding effective rehabilitations for such deficits may help to reduce their impact on the social and psychological functioning of individuals. Our aim in this study was to provide clinicians and researchers with useful information with which to conduct new studies on the rehabilitation of object agnosia and prosopagnosia. To accomplish this, we performed a systematic and comprehensive review of the effect of neuropsychological rehabilitation on visual object and prosopagnosia. The Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were followed. In addition, the Single-Case Experimental Design (SCED) and the Critical Appraisal Skills Programme (CASP) scales were used to assess the quality of reporting. Seven articles regarding object agnosia, eight articles describing treatments for prosopagnosia, and two articles describing treatments for both deficits were included. In the light of the studies reviewed, treatments based on analysis of parts seem effective for object agnosia, while prosopagnosia appears to benefit most from treatments relying on holistic/configural processing. However, more attempts at rehabilitation of face and object agnosia are needed to clarify the mechanisms of these processes and possible rehabilitations. Moreover, a publication bias could mask a broader attempt to find effective treatments for visual agnosia and leaving out studies that are potentially more informative.

Apperceptive and associative visual object agnosia in patients with acute ischemic stroke

Visual object agnosia (VOA) is a loss of the ability to recognize visible objects in patients with the intact primary visual functions and in the absence of dementia. The apperceptive and associative variants of VOA are marked out. The apperceptive VOA is thought to be due to «pre-semantic» impairment of visual information processing. The associative VOA is caused by the loss of access to knowledge about the objects, and its semantic subtype is due to the disintegration of this knowledge itself. It is important to diagnose VOA and its variants in time to provide individualized approaches to medical rehabilitation of patients. Case reports of apperceptive and associative VOA in acute ischemic stroke are presented in this paper. These case reports indicate the possibility of the development of apperceptive and associative VOA in unilateral acute ischemic brain lesion. The variants of VOA can be recognized only by a detailed neuropsychological examination.

Visual features drive the category-specific impairments on categorization tasks in a patient with object agnosia

Object and scene recognition both require mapping of incoming sensory information to existing conceptual knowledge about the world. A notable finding in brain-damaged patients is that they may show differentially impaired performance for specific categories, such as for “living exemplars”. While numerous patients with category-specific impairments have been reported, the explanations for these deficits remain controversial. In the current study, we investigate the ability of a brain injured patient with a well-established category-specific impairment of semantic memory to perform two categorization experiments: ‘natural’ vs. ‘manmade’ scenes (experiment 1) and objects (experiment 2). Our findings show that the pattern of categorical impairment does not respect the natural versus manmade distinction. This suggests that the impairments may be better explained by differences in visual features, rather than by category membership. Using Deep Convolutional Neural Networks (DCNNs) as ‘artificial animal models’ we further explored this idea. Results indicated that DCNNs with ‘lesions’ in higher order layers showed similar response patterns, with decreased relative performance for manmade scenes (experiment 1) and natural objects (experiment 2), even though they have no semantic category knowledge, apart from a mapping between pictures and labels. Collectively, these results suggest that the direction of category-effects to a large extent depends, at least in MS′ case, on the degree of perceptual differentiation called for, and not semantic knowledge.

Selective hyperfamiliarity for voices

An 84-year-old man manifested false recognition/misidentification of unfamiliar person after cardiogenic cerebral infarction. He had good visual and hearing acuity, no hemianopsia, unilateral spatial neglect and visual object agnosia. However, he was unable to remember faces of his rehabilitation therapists, and repeatedly misidentified other patients’ visitors and therapists as his family members and friends, without recognizing his mistakes. General cognitive function was preserved with Hasegawa dementia score-revised (HDS-R) 25/30 (cut-off score 20). In terms of recognition of faces, tasks not requiring recognition of facial identity, such as interpreting facial emotions, and gender and age assessment, were relatively preserved, but recognition of family members and celebrities was severely impaired, and matching unfamiliar faces was slightly impaired. Semantic information of family and friends was retained. Although his symptoms resembled associative prosopagnosia, they differed from general associative prosopagnosia in having phonagnosia. MRI lesions were localized in the frontal and temporal lobes including the right anterior temporal lobe, and not in the right occipital and temporal lobes considered to the lesion site of multimodal people recognition disorders manifesting inability of utilization of visual (face) and auditory (voice) cues for person identification. In addition to the facial cognitive impairment, impaired exploratory (monitoring) function of the frontal lobe on the temporal lobe may also contribute to the false recognition/misidentification of this case.

Зрительная объектная агнозия при остром ишемическом инсульте: первый нейровизуализационный биомаркер

Study Objective: To demonstrate the potential use of peripheral sulcus occipitotemporalis involvement as a first neuroimaging biomarker of visual object agnosia in acute ischemic stroke. Study Design: Retrospective study. Materials and Methods. We have examined 76 patients (52 males, 24 females) in peracute or acute hemisphetic (supratentorial) ischemic stroke. The age of participants was 66.5 ± 6.7 years. The examination involved neurological, neuropsychologic, neuroimaging and eye checks. Any disturbances of the visual object gnosis were diagnosed with the Object Decision test from the Birmingham Object Recognition Battery. According to brain CT and MRI results, all patients underwent assessment of their sulcus occipitotemporalis involvement. Study Results. Stroke-related visual object agnosia was diagnosed in 7 (9.2%) patients. Statistically significant correlation between foci localisation in the sulcus occipitotemporalis and visual object agnosia development (χ2 = 64.2; р < 0.001) has been demonstrated. The sensitivity of sulcus occipitotemporalis involvement as a biomarker of visual object agnosia in acute ischemic stroke was 85.7%, while the specificity was 100%. Conclusion. Sulcus occipitotemporalis involvement in acute ischemic stroke can be used as a neuroimaging biomarker of visual object agnosia. Keywords: visual agnosia, object agnosia, ischemic stroke, neuroimaging, sulcus occipitotemporalis.

Selective defects of face familiarity associated to a left temporo-occipital lesion

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. Our patient failed to feel familiarity feelings even with very well-known famous faces but had neither visual object agnosia nor defects with semantics or naming of celebrities. This was confirmed even when the patient was re-tested a year later. We speculate that a graded lateralization of face processing could be at the basis of occasional cases of prosopagnosia.

Зрительная объектная агнозия и агнозия новых топографических ориентиров у пациентов с острым полушарным ишемическим инсультом

The purpose — to estimate the frequency of visual general objects agnosia and novel landmarks agnosia in patients with acute ischemic stroke and to describe the clinical manifestations of these phenomena and association between them. Materil and methods. 75 patients with ischemic stroke were enrolled. Computed tomography and/or magnetic resonance scan to confirm the ischemic lesion, neurological, ophthalmological and neuropsychological examination were performed in all patients. Visual perception skills (gnosis) were measured by Birmingham Object Recognition Battery tests and authors’ Novel landmarks recognition test. Results. 8 out of 75 patients (10,7%) had visual agnosia documented by the neuropsychological testing, of these 3 patients had question-induced complaints («clinically evident» agnosia, group 1) and 5 patients had no complaints («clinically blurred» agnosia, group 2). 67 patients (89,3%) were not agnostic (group 3). The patients of the 1st and 2nd groups performed perception (gnosis) test significantly worse compared with those of the 3rd group while group 1 demonstrated significantly worse test results than group 2. A significant positive correlation was found between the results of Birmingham Object Recognition Battery tests and the Novel landmarks recognition test. Conclusion. General objects and landmarks recognition is impaired in 10,7% patients with acute ischemic hemispheric stroke. As a rule, general object agnosia is associated with landmark agnosia. Visual general objects and landmarks agnosia may be «clinically evident» verified by the patients’ question-induced complaints as well as by the results of neuropsychological testing, or «clinically blurred», verified only by testing. The test results were statistically significantly worse in «clinically evident» than in «clinically blurred» visual agnosia.

Prosopagnosia without object agnosia? A systematic study of a large sample of developmental cases

Prosopagnosia without object agnosia? A systematic study of a large sample of developmental cases

Visual perceptual disorders in Alzheimer's disease

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. Overall, both low-level and high-level visual perception disorders seem quite common in Alzheimer's disease, including, on a low-level, loss of visual field, decreased acuity and contrast sensitivity, and impaired color vision, and on a high-level, impaired color vision, motion perception, visuospatial deficits, object agnosia, prosopagnosia and impaired recognition of facial emotional expressions. Professionals working with Alzheimer's disease should be aware of visuoperceptual deficits, which could impair the quality of life of the patients, and distort the results of neuropsychological tests using visual material. Moreover, some tests assessing visual perception could be of interest for early diagnosis of the disease.

Evaluating object recognition ability in developmental prosopagnosia using the Cambridge Car Memory Test

ABSTRACTIndividuals with developmental prosopagnosia (DP) sometimes experience object identification difficulties in addition to problems recognizing faces. To better understand the distribution of non-face object recognition ability in this population, we administered the Cambridge Car Memory Test (CCMT) – a leading, standardized measure of object recognition ability – to a large sample of DPs (N = 46). When considered as a single group, the DPs scored lower than matched controls. This finding provides further evidence that developmental object agnosia (DOA) may be more common in DP than in the general population. Relative to the DPs’ face recognition deficits, however, car matching deficits were small and inconsistent. In fact, we observed a striking range of CCMT performance in our DP sample. While some DPs performed extremely poorly, many more achieved scores within one standard deviation of the typical mean, and several DP participants achieved excellent CCMT scores comparable with the best controls.

Зрительная предметная агнозия сложных форм у больных с острым ишемическим инсультом

Зрительная предметная агнозия сложных форм у больных с острым ишемическим инсультом

Functional connectivity and the failure to retrieve meaning from shape in visual object agnosia

The neural mechanisms underlying the access to object knowledge from early representations of shape are little known. Functional imaging studies support the view that representations of visual properties are distributed across occipito-temporal cortex of both cerebral hemispheres. By contrast, brain lesion studies show that focal occipito-temporal damage may lead to object agnosia – a specific impairment of object recognition. How does distributed processing fit with functional specialization implied by the existence of stimulus-specific agnosias? Using fMRI we studied functional connectivity (FC) in a patient with object agnosia following left lateral occipital damage. Despite intact global and local processing of 2D and 3D object structure, the patient made consistent object identification errors. Seven experiments testing naming, visual matching or object priming showed that his errors mainly reflected the global shape similarity between objects. Compared to controls the patient exhibited strongly reduced FC between the damaged left and the intact right medial/lateral occipital cortex. In addition, controls showed stronger connectivity between the right occipital cortex and the left and right inferior and anterior temporal cortices. Interestingly, the patient also showed compensatory increases of FC between dorsal occipital and medial parietal cortex. These findings show that focal damage to the lateral occipital cortex may have global effects on representations of objects in bilateral occipito-temporal cortex, thus supporting the view that bilaterally distributed coding is necessary for the retrieval of associative knowledge from shape.

Posterior Cortical Atrophy: A longitudinal neurocognitive case study.

Posterior Cortical Atrophy (PCA) is a neurodegenerative disease that first develops in the occipital-parietal-temporal cortex. While its major pathological cause is the same as that of Alzheimer's disease (e.g. Tang-Wai & colleagues), the development of the cognitive changes over its course is quite different. Here we present a 6-year longitudinal account of the neurocognitive profile of a highly intelligent man (BG), starting from the year of his diagnosis to that of his death. Despite his normal visual acuity and visual fields, BG initially reported reading difficulties. Early in his disease, he had deficits in visual attention, processing speed and recognition. His recognition difficulties first presented as alexia without agraphia, followed by topographical disorientation, prosopagnosia, simultagnosia, and object agnosia. Next, his visuo-constructional, arithmetic skills, and visual memory gradually declined. Relative to his severe visuo-perceptual and recognition difficulties, his abilities to reach for objects remained functional. Serial MRI brains demonstrated progressive left-more-than-right occipital, temporal and parietal atrophy with relative sparing of the hippocampi. Four years following diagnosis, BG could no longer perform any visual tasks and started to develop significant expressive language difficulties. Over the full course of the disease, his motor abilities, verbal recognition and verbal logical memory remained functional, and his practical reasoning normal. BG's case illustrates that the neurodegenerative process involve in PCA can first affect the visuo-cognitive functions typical of the ventral system, extend to all functions dependent on the posterior areas, and eventually to language areas, all while sparing areas responsible for practical and logical verbal reasoning. Meeting abstract presented at VSS 2018

The Visual Agnosias and Related Disorders.

There are many disorders of higher visual processing that result from damage to specific areas of the cerebral cortex that have a specific role in processing certain aspects (modalities) of vision. These can be grouped into those that affect the ventral, or "what?", pathway (e.g., object agnosia, cerebral achromatopsia, prosopagnosia, topographagnosia, and pure alexia), and those that affect the dorsal, or "where?", pathway (e.g., akinetopsia, simultanagnosia, and optic ataxia). This article reviews pertinent literature, concentrating on recent developments in basic science research and studies of individual patients. An overview of the current understanding of higher cerebral visual processing is followed by a discussion of the various disorders listed above. There has been considerable progress in the understanding of how the extrastriate visual cortex is organized, specifically in relation to functionally specialized visual areas. This permits a better understanding of the individual visual agnosias resulting from damage to these areas.

Minor Hemisphere Major Syndromes.

A right "minor hemisphere" does not exist as the right hemisphere is dominant for awareness (nosognosia), spatial attention, emotional regulation, facial and voice expressions, visual recognition, and topographical orientation. Without the right hemisphere, the world would be flat, deprived of general and spatial attentions, pointing preferentially to the right side of the space, lacking visual experiences and emotions, exhibiting diminished awareness of the self and environment. Clinical-related syndromes of the right hemisphere are unilateral spatial neglect, object and face visual agnosia, the anosognosia for hemiparesis and/or hemianopia, misidentification syndromes, mania, and other obsessions for the food and the body. Another key function of the right hemisphere is the modulation of the emotional processes of the linguistic communication (as prosody and facial expressions), and the tuning of some holistic aspects of language as the understanding of the abstract and figurative characters. The great mysteries of the right brain hemisphere concern the origin of the emotional nature of the human being, the way by which cognition interacts with perception and finally the human consciousness. Multidisciplinary researches in the domains of neurology, cognitive psychology, neuropsychiatry, functional neuroimaging, and neurophysiology will reveal in the future some of these mysteries.

The still under-investigated role of cognitive deficits in PML diagnosis

BackgroundDespite cognitive deficits frequently represent the first clinical manifestations of Progressive Multifocal Leukoencephalopathy (PML) in Natalizumab-treated MS patients, the importance of cognitive deficits in PML diagnosis is still under-investigated. The aim of the current study is to investigate the cognitive deficits at PML diagnosis in a group of Italian patients with PML.MethodsThirty-four PML patients were included in the study. The demographic and clinical data, the lesion load and localization, and the longitudinal clinical course was compared between patients with (n = 13) and without (n = 15) cognitive deficit upon PML suspicion (the remaining six patients were asymptomatic). Clinical presentation of cognitive symptoms was described in detail.ResultAfter symptoms detection, the time to diagnosis resulted to be shorter for patients presenting with cognitive than for patients with non cognitive onset (p = 0.03). Within patients with cognitive onset, six patients were presenting with language and/or reading difficulties (46.15%); five patients with memory difficulties (38.4%); three patients with apraxia (23.1%); two patients with disorientation (15.3%); two patients with neglect (15.3%); one patients with object agnosia (7.7%), one patient with perseveration (7.7%) and one patient with dementia (7.7%). Frontal lesions were less frequent (p = 0.03), whereas temporal lesions were slightly more frequent (p = 0.06) in patients with cognitive deficits. The longitudinal PML course seemed to be more severe in cognitive than in non cognitive patients (F = 2.73, p = 0.03), but differences disappeared (F = 1.24, p = 0.29) when balancing for the incidence of immune reconstitution syndrome and for other treatments for PML (steroids, plasma exchange (PLEX) and other therapies (Mefloquine, Mirtazapine, Maraviroc).ConclusionCognitive deficits at PML onset manifest with symptoms which are absolutely rare in MS. Their appearance in MS patients should strongly suggest PML. Clinicians should be sensitive to the importance of formal neuropsychological evaluation, with particular focus on executive function, which are not easily detected without a formal assessment.

Functional modulation of contralateral bias in early and object-selective areas after stroke of the occipital ventral cortices

Object agnosia is a rare symptom, occurring mainly after bilateral damage of the ventral visual cortex. Most patients suffering from unilateral ventral lesions are clinically non-agnosic. Here, we studied the effect of unilateral occipito-temporal lesions on object categorization and its underlying neural correlates in visual areas. Thirteen non-agnosic stroke patients and twelve control subjects performed an event-related rapid object categorization task in the fMRI scanner where images were presented either to the left or to the right of a fixed point. Eight patients had intact central visual fields within at least 10° eccentricity while five patients showed an incomplete hemianopia. Patients made more errors than controls for both contra- and ipsilesional presentation, meaning that object categorization was impaired bilaterally in both patient groups. The activity in cortical visual areas is usually higher when a stimulus is presented contralaterally compared to presented ipsilaterally (contralateral bias). A region of interest analysis of early visual (V1–V4) and object-selective areas (lateral occipital complex, LOC; fusiform face area, FFA; and parahippocampal place area, PPA) revealed that the lesioned-hemisphere of patients showed reduced contralateral bias in early visual areas and LOC. In contrast, literally no contralateral bias in FFA and PPA was found. These findings indicate disturbed processing in the lesioned hemisphere, which might be related to the processing of visually presented objects. Thus, unilateral occipito-temporal damage leads to altered contralateral bias in the lesioned hemisphere, which might be the cause of impaired categorization performance in both visual hemifields in clinically non-agnosic patients. We conclude that both hemispheres need to be functionally intact for unimpaired object processing.