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Annals of Indian Academy of Neurology Oct 2022Cerebral visual disorders include a range of common and rare deficits. They can be divided into effects on low-, intermediate-, and high-level forms of visual...
Cerebral visual disorders include a range of common and rare deficits. They can be divided into effects on low-, intermediate-, and high-level forms of visual processing. Low-level deficits are various forms of homonymous hemifield scotomata, which affect all types of vision within their borders. Intermediate-level deficits refer to impairments of colour or motion perception, which affect either one hemifield or the entire field when lesions are bilateral. High-level deficits are divided into those of the ventral (occipitotemporal) or dorsal (occipitoparietal) stream. Occipitotemporal lesions affect various aspects of object recognition, ranging from general visual agnosia to selective agnosias, such as prosopagnosia or topographagnosia from right or bilateral lesions, and pure alexia from left-sided lesions. Occipitoparietal lesions cause the various components of Bálint syndrome, namely, simultanagnosia, optic ataxia, and ocular motor apraxia. They can also cause other impairments of visuospatial or visuotemporal processing, such as astereopsis and sequence-agnosia. Because of anatomic proximity, certain deficits cluster together to form a number of cerebral visual syndromes. Treatment of these disorders remains challenging, with frequent reliance on strategic substitutions rather than restorative approaches.
PubMed: 36589033
DOI: 10.4103/aian.aian_136_22 -
Brain Imaging and Behavior Jun 2022Simultanagnosia is a common symptom of posterior cortical atrophy, and its association with brain structural and functional changes remains unclear. In our study, 18...
Simultanagnosia is a common symptom of posterior cortical atrophy, and its association with brain structural and functional changes remains unclear. In our study, 18 posterior cortical atrophy patients with simultanagnosia, 29 patients with Alzheimer's disease and 20 cognitively normal controls were recruited and subjected to full neuropsychological evaluation, including simultanagnosia tests, and structural and resting-state functional MRI. The gray matter volume was assessed by voxel-based morphometry, while the intrinsic functional connectivity was evaluated using the reduced gray matter volume regions of interest as the seed. In contrast to the patients with Alzheimer's disease, those with posterior cortical atrophy showed the following: (1) markedly lower simultanagnosia test scores, (2) an altered regional gray matter volume of the left middle occipital gyrus and ventral occipital areas, and (3) lowered intrinsic functional connectivity with the left middle occipital gyrus, left lingual gyrus and right middle occipital gyrus separately. Additionally, the gray matter volume of the left middle occipital gyrus and left inferior occipital gyrus were each correlated with simultanagnosia in posterior cortical atrophy patients. The intrinsic functional connectivity of the left middle occipital gyrus with the right superior occipital gyrus and that of the right middle occipital gyrus with the left superior parietal gyrus were also correlated with simultanagnosia in posterior cortical atrophy patients. In summary, this study indicated that simultanagnosia is associated with gray matter reductions and decreased functional connectivity in the left middle occipital gyrus and the left inferior occipital gyrus in patients with posterior cortical atrophy.
Topics: Alzheimer Disease; Atrophy; Brain; Brain Mapping; Gray Matter; Humans; Magnetic Resonance Imaging
PubMed: 34787788
DOI: 10.1007/s11682-021-00568-8 -
Proceedings (Baylor University. Medical... Jan 2020Simultanagnosia is a well-known neurologic symptom characterized by the inability to conceptualize the whole picture despite being able to see individual elements within...
Simultanagnosia is a well-known neurologic symptom characterized by the inability to conceptualize the whole picture despite being able to see individual elements within a visual scene. The pathophysiology involves a lesion to the bilateral parieto-occipital lobe. We report two unusual cases of simultanagnosia and juxtaposed homonymous visual field loss involving aqueductal stenosis-related obstructive hydrocephalus and cardiac arrest due to Brugada syndrome. Clinicians should be aware that simultanagnosia can be the presenting symptom of neuro-ophthalmic disease.
PubMed: 32063790
DOI: 10.1080/08998280.2019.1656013 -
NeuroImage Jul 2021Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also with impairments in the...
Lesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also with impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies and lesion patterns observed in patients with simultanagnosia and agnosia for object orientation suggest similar brain regions to be involved in perception of global shapes and processing of objects in atypical ('non-canonical') orientation. In a localizer experiment, we identified individual temporo-parietal brain areas involved in global shape perception and found significantly higher BOLD signals during the processing of non-canonical compared to canonical objects. In a multivariate approach, we demonstrated that posterior temporo-parietal brain areas show distinct voxel patterns for non-canonical and canonical objects and that voxel patterns of global shapes are more similar to those of objects in non-canonical compared to canonical viewing conditions. These results suggest that temporo-parietal brain areas are not only involved in global shape perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting specific dorsal contributions in more demanding viewing conditions.
Topics: Adult; Female; Humans; Magnetic Resonance Imaging; Male; Parietal Lobe; Photic Stimulation; Recognition, Psychology; Temporal Lobe; Visual Perception; Young Adult
PubMed: 33757908
DOI: 10.1016/j.neuroimage.2021.117982 -
Neuropsychologia Oct 2021Attentional resource and distribution are specifically impaired in simultanagnosia, and also in the visuo-attentional form of developmental dyslexia. Both clinical...
Attentional resource and distribution are specifically impaired in simultanagnosia, and also in the visuo-attentional form of developmental dyslexia. Both clinical conditions are conceived as a limitation of simultaneous visual processing after superior parietal lobule (SPL) dysfunction (review in Valdois et al., 2019). However, a reduced space-based attentional window (i.e. a limited visual eccentricity at which the target object can be identified, Khan et al. 2016) has been demonstrated in simultanagnosia versus a reduced object-based span (i.e. a limited number of objects processed at each fixation, Bosse et al., 2007) in developmental dyslexia. In healthy individuals, the cost in reaction times per item in serial search tasks suggests that a group of objects is processed simultaneously at a time, but this group is also undefined and depends on the visual complexity of the task. Healthy individuals and a patient with simultanagnosia performed serial search tasks involving either symbols (made of separable features) or objects made of non-separable features, and with distractors that were either all identical or all dissimilar. We used a moving window paradigm to determine whether the task was performed with a "working space" versus a "working span" limitation in control group and in patient with bilateral SPL damage. We found that healthy individuals performed search in a color task comprising non-separable feature objects and dissimilar distractors with a limited space-based attentional window; this attentional window, as well as the mean saccade amplitude used to displace it across the visual display, were independent of set size, thus inconsistent with an object-based attentional span. In the symbol task comprising a feature-absent search in which all feature-present distractors were dissimilar, we observed that mean saccade amplitude decreased with set size and that search performance could not be mimicked by a moving window of a single diameter; instead participants seemed to process a fixed number of symbols at a time (object-based span). Following bilateral SPL lesions, patient IG demonstrated a similar space-based search process in the color search task with a normal attentional window. In contrast, her cost-per-item in the symbol task increased dramatically, demonstrating a clear deficit of simultaneous object perception. These results confirmed the specific contribution of the SPL to the visual processing of multiple objects made of separable features (like letters), and more dramatically when they are all different, which explains the specific difficulty for a reading beginner in case of SPL dysfunction.
Topics: Cognition; Female; Humans; Parietal Lobe; Reaction Time; Saccades; Visual Perception
PubMed: 34474063
DOI: 10.1016/j.neuropsychologia.2021.108013 -
Revista Colombiana de Psiquiatria May 2022Social distancing measures due to the COVID-19 pandemic prevented many children with neurodevelopmental disorders from accessing face-to-face treatments....
INTRODUCTION
Social distancing measures due to the COVID-19 pandemic prevented many children with neurodevelopmental disorders from accessing face-to-face treatments. Telerehabilitation grew at this time as an alternative therapeutic tool. In this study we analysed remote cognitive rehabilitation in neurodevelopmental disorders.
METHODS
This was a prospective, quasi-experimental (before-after) study that included 22 patients (mean age 9.41 years) with neurodevelopmental disorders who had telerehabilitation for over six months.
RESULTS
After six months of telerehabilitation, a statistically significant improvement was found with a large effect size in these areas: attention (sustained, selective and divided), executive functions (verbal and visual working memory, categorisation, processing speed), visuospatial skills (spatial orientation, perceptual integration, perception, simultanagnosia) and language (comprehensive and expressive). On the Weiss Functional Impairment Scale, all areas (family, learning and school, self-concept, activities of daily living, risk activities) improved with statistical significance. We found a positive correlation between the number of sessions and the improvement observed in executive functions (visual working memory, processing speed), attention (sustained attention, divided attention) and visuospatial skills (spatial orientation, perceptual integration, perception, simultanagnosia). We did not find statistical significance between the family structure and the number of sessions carried out. A high degree of perception of improvement and satisfaction was observed in the parents.
CONCLUSIONS
Telerehabilitation is a safe alternative tool which, although it does not replace face-to-face therapy, can achieve significant cognitive and functional improvements in children with neurodevelopmental disorders.
PubMed: 35600217
DOI: 10.1016/j.rcp.2022.03.003 -
Indian Journal of Ophthalmology Jan 2020Simultanagnosia resulting from dorsal stream dysfunction is an under recognized condition. In this case report we describe the case of a young woman who developed...
Simultanagnosia resulting from dorsal stream dysfunction is an under recognized condition. In this case report we describe the case of a young woman who developed posterior reversible encephalopathy syndrome (PRES), and who recovered visual acuities of 20/20 in each eye, along with normal visual fields and contrast sensitivities, yet experienced persistent symptoms of perceptual dysfunction. Detailed and systematic history taking revealed consistent visual difficulties typical of dorsal stream dysfunction. After a detailed explanation of her symptomatology and training in a range of strategies to cope, the patient experienced a great improvement in her day-to-day functioning.
Topics: Adult; Agnosia; Brain; Female; Humans; Magnetic Resonance Imaging; Posterior Leukoencephalopathy Syndrome; Vision Disorders; Visual Acuity
PubMed: 31856545
DOI: 10.4103/ijo.IJO_807_19 -
MedRxiv : the Preprint Server For... Nov 2023Posterior Cortical Atrophy (PCA) is a syndrome characterized by a progressive decline in higher-order visuospatial processing, leading to symptoms such as space...
INTRODUCTION
Posterior Cortical Atrophy (PCA) is a syndrome characterized by a progressive decline in higher-order visuospatial processing, leading to symptoms such as space perception deficit, simultanagnosia, and object perception impairment. While PCA is primarily known for its impact on visuospatial abilities, recent studies have documented language abnormalities in PCA patients. This study aims to delineate the nature and origin of language impairments in PCA, hypothesizing that language deficits reflect the visuospatial processing impairments of the disease.
METHODS
We compared the language samples of 25 patients with PCA with age-matched cognitively normal (CN) individuals across two distinct tasks: a visually-dependent picture description and a visually-independent job description task. We extracted word frequency, word utterance latency, and spatial relational words for this comparison. We then conducted an in-depth analysis of the language used in the picture description task to identify specific linguistic indicators that reflect the visuospatial processing deficits of PCA.
RESULTS
Patients with PCA showed significant language deficits in the visually-dependent task, characterized by higher word frequency, prolonged utterance latency, and fewer spatial relational words, but not in the visually-independent task. An in-depth analysis of the picture description task further showed that PCA patients struggled to identify certain visual elements as well as the overall theme of the picture. A predictive model based on these language features distinguished PCA patients from CN individuals with high classification accuracy.
DISCUSSION
The findings indicate that language is a sensitive behavioral construct to detect visuospatial processing abnormalities of PCA. These insights offer theoretical and clinical avenues for understanding and managing PCA, underscoring language as a crucial marker for the visuospatial deficits of this atypical variant of Alzheimer's disease.
PubMed: 38045263
DOI: 10.1101/2023.11.21.23298864 -
Journal of Clinical Neurology (Seoul,... May 2024
PubMed: 38627231
DOI: 10.3988/jcn.2023.0468