Unusual Pattern of Reading Errors in a Patient with Posterior Cortical Atrophy

Posterior cortical atrophy (PCA) is a degenerative condition characterized by a progressive deterioration of visual processing. Dyslexia constitutes an early and frequent visual symptom of the disease and previous comprehensive investigations in series of individuals have extensively documented a characteristic abundance of visual errors as the most prevalent error category in this population. Here we describe the profile of a patient with PCA, C.P., who presents an unusual prevalence of phonological, instead of purely visual, errors in his reading, in the context of an otherwise classic PCA phenotype. In keeping with the well-known PCA profile, C.P. exhibited deficits at the pre-lexical level with elements of crowding and defective early visual processing impairments but additionally showed an unusually prominent disruption of phonological processing. We also argue that our patient may have a refractory access type deficit in reading given that accuracy doubled with the introduction of a five-second response-stimulus interval. To our knowledge, no previous case of a refractory deficit affecting word reading has been reported in PCA. Our examination builds on previous knowledge about reading behaviour in PCA and describes a singular example of the rich phenotypic heterogeneity within the syndrome.

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Foveal crowding in posterior cortical atrophy: A specific early-visual-processing deficit affecting word reading

Cognitive Neuropsychology ◽

10.1080/02643290701754240 ◽

2007 ◽

Vol 24 (8) ◽

pp. 843-866 ◽

Cited By ~ 27

Author(s):

Sebastian J. Crutch ◽

Elizabeth K. Warrington

Keyword(s):

Visual Processing ◽

Word Reading ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Early Visual Processing ◽

Processing Deficit

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Latent atrophy factors related to phenotypical variants of posterior cortical atrophy

Neurology ◽

10.1212/wnl.0000000000010362 ◽

2020 ◽

Vol 95 (12) ◽

pp. e1672-e1685 ◽

Cited By ~ 1

Author(s):

Colin Groot ◽

B.T. Thomas Yeo ◽

Jacob W. Vogel ◽

Xiuming Zhang ◽

Nanbo Sun ◽

...

Keyword(s):

Gray Matter ◽

Visual Processing ◽

Space Perception ◽

Object Perception ◽

Cortical Atrophy ◽

Intracranial Volume ◽

Posterior Cortical Atrophy ◽

Modeling Framework ◽

Β Amyloid ◽

The Right

ObjectiveTo determine whether atrophy relates to phenotypical variants of posterior cortical atrophy (PCA) recently proposed in clinical criteria (i.e., dorsal, ventral, dominant-parietal, and caudal) we assessed associations between latent atrophy factors and cognition.MethodsWe employed a data-driven Bayesian modeling framework based on latent Dirichlet allocation to identify latent atrophy factors in a multicenter cohort of 119 individuals with PCA (age 64 ± 7 years, 38% male, Mini-Mental State Examination 21 ± 5, 71% β-amyloid positive, 29% β-amyloid status unknown). The model uses standardized gray matter density images as input (adjusted for age, sex, intracranial volume, MRI scanner field strength, and whole-brain gray matter volume) and provides voxelwise probabilistic maps for a predetermined number of atrophy factors, allowing every individual to express each factor to a degree without a priori classification. Individual factor expressions were correlated to 4 PCA-specific cognitive domains (object perception, space perception, nonvisual/parietal functions, and primary visual processing) using general linear models.ResultsThe model revealed 4 distinct yet partially overlapping atrophy factors: right-dorsal, right-ventral, left-ventral, and limbic. We found that object perception and primary visual processing were associated with atrophy that predominantly reflects the right-ventral factor. Furthermore, space perception was associated with atrophy that predominantly represents the right-dorsal and right-ventral factors. However, individual participant profiles revealed that the large majority expressed multiple atrophy factors and had mixed clinical profiles with impairments across multiple domains, rather than displaying a discrete clinical–radiologic phenotype.ConclusionOur results indicate that specific brain behavior networks are vulnerable in PCA, but most individuals display a constellation of affected brain regions and symptoms, indicating that classification into 4 mutually exclusive variants is unlikely to be clinically useful.

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The Evolution of Alexia in Two Cases of Posterior Cortical Atrophy

Behavioural Neurology ◽

10.1155/2011/949530 ◽

2011 ◽

Vol 24 (3) ◽

pp. 229-236 ◽

Cited By ~ 6

Author(s):

Eleonora Catricalà ◽

Pasquale A. Della Rosa ◽

Paola Ortelli ◽

Valeria Ginex ◽

Alessandra Marcone ◽

...

Keyword(s):

Clinical Features ◽

Visual Processing ◽

Single Photon ◽

Photon Emission ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Disease Evolution ◽

Neuropsychological Dysfunction ◽

Reading Impairment ◽

Uncommon Presentation

Posterior cortical atrophy (PCA) is an uncommon presentation of Alzheimer's disease (AD), characterised by prevalent anatomo-functional involvement of posterior cortical areas. Accordingly, the main clinical features at onset are disorders of high-order visual processing, such as alexia and impairments of visuo-spatial and visuo-constructional abilities. The clinical features in the early stages of disease are variable, and they have been suggested to stem from prevalent ventral or dorsal brain pathology, and/or asymmetric hemispheric involvement. With disease progression, these differences tend to blur with the increasing severity of neuropsychological dysfunction. We report two PCA patients showing different patterns of reading impairment (respectively, letter-by-letter reading and neglect dyslexia). A follow-up study suggested that the qualitative features of alexia remain distinctive with disease evolution. In addition, single photon emission tomography (SPECT) studies revealed different patterns of hypoperfusion, consistent with the alexia types. A careful reading assessment can provide important insights to the pattern of progression of the disease in patients with PCA up to the late stages of the pathology.

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Longitudinal neuroanatomical and cognitive progression of posterior cortical atrophy

Brain ◽

10.1093/brain/awz136 ◽

2019 ◽

Vol 142 (7) ◽

pp. 2082-2095 ◽

Cited By ~ 18

Author(s):

Nicholas C Firth ◽

Silvia Primativo ◽

Razvan-Valentin Marinescu ◽

Timothy J Shakespeare ◽

Aida Suarez-Gonzalez ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Visual Processing ◽

Phenotypic Diversity ◽

Rate Of Change ◽

Tissue Loss ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Brain Volumes ◽

Regional Brain

Abstract Posterior cortical atrophy is a clinico-radiological syndrome characterized by progressive decline in visual processing and atrophy of posterior brain regions. With the majority of cases attributable to Alzheimer’s disease and recent evidence for genetic risk factors specifically related to posterior cortical atrophy, the syndrome can provide important insights into selective vulnerability and phenotypic diversity. The present study describes the first major longitudinal investigation of posterior cortical atrophy disease progression. Three hundred and sixty-one individuals (117 posterior cortical atrophy, 106 typical Alzheimer’s disease, 138 controls) fulfilling consensus criteria for posterior cortical atrophy-pure and typical Alzheimer’s disease were recruited from three centres in the UK, Spain and USA. Participants underwent up to six annual assessments involving MRI scans and neuropsychological testing. We constructed longitudinal trajectories of regional brain volumes within posterior cortical atrophy and typical Alzheimer’s disease using differential equation models. We compared and contrasted the order in which regional brain volumes become abnormal within posterior cortical atrophy and typical Alzheimer’s disease using event-based models. We also examined trajectories of cognitive decline and the order in which different cognitive tests show abnormality using the same models. Temporally aligned trajectories for eight regions of interest revealed distinct (P < 0.002) patterns of progression in posterior cortical atrophy and typical Alzheimer’s disease. Patients with posterior cortical atrophy showed early occipital and parietal atrophy, with subsequent higher rates of temporal atrophy and ventricular expansion leading to tissue loss of comparable extent later. Hippocampal, entorhinal and frontal regions underwent a lower rate of change and never approached the extent of posterior cortical involvement. Patients with typical Alzheimer’s disease showed early hippocampal atrophy, with subsequent higher rates of temporal atrophy and ventricular expansion. Cognitive models showed tests sensitive to visuospatial dysfunction declined earlier in posterior cortical atrophy than typical Alzheimer’s disease whilst tests sensitive to working memory impairment declined earlier in typical Alzheimer’s disease than posterior cortical atrophy. These findings indicate that posterior cortical atrophy and typical Alzheimer’s disease have distinct sites of onset and different profiles of spatial and temporal progression. The ordering of disease events both motivates investigation of biological factors underpinning phenotypic heterogeneity, and informs the selection of measures for clinical trials in posterior cortical atrophy.

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Data-driven detection of latent atrophy factors related to phenotypical variants of posterior cortical atrophy

10.1101/679225 ◽

2019 ◽

Author(s):

Colin Groot ◽

B.T. Thomas Yeo ◽

Jacob W Vogel ◽

Xiuming Zhang ◽

Nanbo Sun ◽

...

Keyword(s):

Gray Matter ◽

Visual Processing ◽

Amyloid Β ◽

Space Perception ◽

Object Perception ◽

Data Driven ◽

Cortical Atrophy ◽

Intracranial Volume ◽

Posterior Cortical Atrophy ◽

The Right

AbstractPosterior cortical atrophy is a clinical-radiological syndrome characterized by visual processing deficits and atrophy in posterior parts of the brain, most often caused by Alzheimer’s disease pathology. Recent consensus criteria describe four distinct phenotypical variants of posterior cortical atrophy defined by clinical and radiological features; i) object perception/occipitotemporal (ventral), ii) space perception/temporoparietal (dorsal), iii) non-visual/dominant parietal and iv) primary visual (caudal). We employed a data-driven approach to identify atrophy factors related to these proposed variants in a multi-center cohort of 119 individuals with posterior cortical atrophy (age: 64 SD 7, 38% male, MMSE: 21 SD 5, 71% amyloid-β positive, 29% amyloid-β status unknown). A Bayesian modelling framework based on latent Dirichlet allocation was used to compute four latent atrophy factors in accordance with the four proposed variants. The model uses standardized gray matter density images as input (adjusted for age, sex, intracranial volume, field strength and whole-brain gray matter volume) and provides voxelwise probabilistic maps for all atrophy factors, allowing every individual to express each factor to a degree without a priori classification. The model revealed four distinct yet partially overlapping atrophy factors; right-dorsal, right-ventral, left-ventral, and limbic. Individual participant profiles revealed that the vast majority of participants expressed multiple factors, rather than predominantly expressing a single factor. To assess the relationship between atrophy factors and cognition, neuropsychological test scores covering four posterior cortical atrophy-specific cognitive domains were assessed (object perception, space perception, non-visual parietal functions and primary visual processing) and we used general linear models to examine the association between atrophy factor expression and cognition. We found that object perception and primary visual processing were associated with atrophy that predominantly reflects the right-ventral factor. Furthermore, space perception was associated with atrophy that predominantly represents the right-ventral and right-dorsal factors. Similar to the atrophy factors, most participants had mixed clinical profiles with impairments across multiple domains. However, when selecting four participants with an isolated impairment, we observed atrophy patterns and factor expressions that were largely in accordance with the hypothesized variants. Taken together, our results indicate that variants of posterior cortical atrophy exist but these constitute phenotypical extremes and most individuals fall along a broad clinical-radiological spectrum, indicating that classification into four mutually exclusive variants is unlikely to be clinically useful.

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Integration of Impaired Visual as Well as Impaired Phonological Information Can Cause Reading Errors

Perception ◽

10.1068/v970019 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 116-116 ◽

Cited By ~ 2

Author(s):

P L Cornelissen ◽

P C Hansen ◽

J F Stein

Keyword(s):

Motion Detection ◽

Phonological Processing ◽

Reading Ability ◽

Word Reading ◽

Coherent Motion ◽

Phonological Information ◽

Visual Stream ◽

Reading Errors ◽

Single Word Reading ◽

Printed Word

Developmental dyslexia is a common problem amongst school children (5% – 10% are afflicted), yet controversy surrounds the explanation for its cause. Fluent reading requires rapid association of visual with phonological information—therefore problems with either visual or phonological processing could cause reading difficulties. It is known that dyslexics’ speech perception is often impaired, giving rise to ‘fuzzy’ or ‘underspecified’ phonological representations. This leads, in turn, to difficulties with letter-to-sound mapping during reading. Dyslexic individuals also find it unusually difficult to detect flickering or moving visual stimuli, consistent with impaired processing in the magnocellular visual stream. This raises the question of whether dyslexics' reading problems may be caused not only by abnormal phonological processing but also by magnocellular impairment. We suggest that, when children read, impaired magnocellular function may degrade information about where letters are positioned with respect to each other. We predicted that this might cause reading errors which contain sounds not represented in the printed word. We call these orthographically inconsistent nonsense errors ‘letter’ errors. To test this idea we assessed magnocellular function in 58 children by using a coherent-motion detection task. We then gave these children a single-word reading task and found that the likelihood of them making ‘letter’ errors was best explained by independent contributions from motion detection (ie magnocellular function) and phonological awareness (assessed by a spoonerism task). This result held even when chronological age, reading ability, and IQ were controlled for. These findings suggest that, when visual and phonological information is integrated during reading, impairments in both domains may indeed affect how children read.

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Very early-onset posterior cortical atrophy

Aktuelle Neurologie ◽

10.1055/s-2006-953087 ◽

2006 ◽

Vol 33 (S 1) ◽

Author(s):

W.G. Janzarik ◽

S. Rauer ◽

C. Weiller ◽

K. Schmidtke

Keyword(s):

Early Onset ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy

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Manipulations of the Response-Stimulus Intervals as a Factor Inducing Controlled Amount of Reaction Time Intra-Individual Variability

Brain Sciences ◽

10.3390/brainsci11050669 ◽

2021 ◽

Vol 11 (5) ◽

pp. 669

Author(s):

Paweł Krukow ◽

Małgorzata Plechawska-Wójcik ◽

Arkadiusz Podkowiński

Keyword(s):

Reaction Time ◽

Simple Reaction Time ◽

Reaction Times ◽

Reaction Time Task ◽

Assessment Method ◽

Individual Variability ◽

Simple Reaction Time Task ◽

Stimulus Interval ◽

Simple Reaction ◽

Response Stimulus

Aggrandized fluctuations in the series of reaction times (RTs) are a very sensitive marker of neurocognitive disorders present in neuropsychiatric populations, pathological ageing and in patients with acquired brain injury. Even though it was documented that processing inconsistency founds a background of higher-order cognitive functions disturbances, there is a vast heterogeneity regarding types of task used to compute RT-related variability, which impedes determining the relationship between elementary and more complex cognitive processes. Considering the above, our goal was to develop a relatively new assessment method based on a simple reaction time paradigm, conducive to eliciting a controlled range of intra-individual variability. It was hypothesized that performance variability might be induced by manipulation of response-stimulus interval’s length and regularity. In order to verify this hypothesis, a group of 107 healthy students was tested using a series of digitalized tasks and their results were analyzed using parametric and ex-Gaussian statistics of RTs distributional markers. In general, these analyses proved that intra-individual variability might be evoked by a given type of response-stimulus interval manipulation even when it is applied to the simple reaction time task. Collected outcomes were discussed with reference to neuroscientific concepts of attentional resources and functional neural networks.

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