What’s “up”? Impaired Spatial Preposition Processing in Posterior Cortical Atrophy

This study seeks to confirm whether lesions in posterior regions of the brain involved in visuo-spatial processing are of functional relevance to the processing of words with spatial meaning. We investigated whether patients with Posterior Cortical Atrophy (PCA), an atypical form of Alzheimer’s Disease which predominantly affects parieto-occipital brain regions, is associated with deficits in working memory for spatial prepositions. Case series of patients with PCA and matched healthy controls performed tests of immediate and delayed serial recall on words from three lexico-semantic word categories: number words (twelve), spatial prepositions (behind) and function words (e.g., shall). The three word categories were closely matched for a number of psycholinguistic and semantic variables including length, bi-/tri-gram frequency, word frequency, valence and arousal. Relative to controls, memory performance of PCA patients on short word lists was significantly impaired on spatial prepositions in the delayed serial recall task. These results suggest that lesions in posterior parieto-occipital regions specifically impair the processing of spatial prepositions. Our findings point to a pertinent role of posterior cortical regions in the semantic processing of words with spatial meaning and provide strong support for modality-specific semantic theories that recognize the necessary contributions of sensorimotor regions to conceptual semantic processing.

Download Full-text

The Difficult Diagnosis of Posterior Cortical Atrophy in a 62-Year-Old Woman

Journal of Geriatric Psychiatry and Neurology ◽

10.1177/0891988719856696 ◽

2019 ◽

Vol 33 (1) ◽

pp. 59-64

Author(s):

Georg C. Ziegler ◽

Axel Haarmann ◽

Christine Daniels ◽

Alexandra Herr

Keyword(s):

Health Care Professionals ◽

Brain Regions ◽

Cortical Atrophy ◽

Csf Biomarkers ◽

Symptom Presentation ◽

Imaging Data ◽

Posterior Cortical Atrophy ◽

Considerable Uncertainty ◽

Affective Symptoms ◽

Diagnostic Difficulties

Posterior cortical atrophy (PCA) describes a rare heterogenous neurodegenerative syndrome with early visuospatial and visuoperceptual deficits due to atrophy of parieto-occipital brain regions. Here, we describe the case of a 62-year-old woman showing severe cognitive impairments as well as hemianopsia and all core symptoms of Bálint's syndrome. Years ago, the patient had complained about a “tunnel view” and concentration problems. The diagnostic results point to a case of PCA with underlying Alzheimer pathology. The disease course until diagnosis lasted for 7 years, reflecting the diagnostic difficulties with this still largely unknown syndrome. The unfamiliar symptom presentation including fluctuations in cognitive performance, affective symptoms, cerebrospinal fluid (CSF) biomarkers, which were at first inconspicuous, and a former suspected diagnosis of dissociative pseudodementia, altogether brought considerable uncertainty to the involved health-care professionals. We conclude that cases of “atypical dementia” presenting with visual symptoms, even if appearing unspecific at first, are suspect of PCA. This case report provides an ostensive overview of PCA, including imaging data, CSF-findings, original drawings and handwriting samples from the patient.

Download Full-text

Atypical form of Alzheimer's disease with prominent posterior cortical atrophy: A review of lesion distribution and circuit disconnection in cortical visual pathways

Vision Research ◽

10.1016/s0042-6989(96)00240-4 ◽

1997 ◽

Vol 37 (24) ◽

pp. 3609-3625 ◽

Cited By ~ 146

Author(s):

Patrick R. Hof ◽

Brent A. Vogt ◽

Constantin Bouras ◽

John H. Morrison

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Visual Pathways ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Atypical Form

Download Full-text

Two hundred and forty-eight cases of visual snow: A review of potential inciting events and contributing comorbidities

Cephalalgia ◽

10.1177/0333102421996355 ◽

2021 ◽

pp. 033310242199635

Author(s):

Dev G Mehta ◽

Ivan Garza ◽

Carrie E Robertson

Keyword(s):

Care Center ◽

Tertiary Care ◽

Case Series ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Retrospective Case ◽

Triggering Events ◽

Perception Disorder ◽

Visual Disturbances

Objective To review characteristics and outcomes of all cases of visual snow seen at our institution, with attention to possible triggering events or comorbidities. Methods This is a retrospective case series of patients seen at our tertiary care center from January 1994 to January 2020. Charts were reviewed if they contained the term “visual snow”. Results Of the 449 charts reviewed, 248 patients described seeing visual snow in part or all of their vision. Thirty-eight reported transient visual snow as their typical migraine aura. Of the remaining 210 patients, 89 were reported to have either an inciting event or contributing comorbidity for their visual snow symptoms, including: Post-concussion (n = 15), dramatic change in migraine or aura (n = 14), post-infection (n = 13), hallucinogen persisting perception disorder (n = 10), ocular abnormalities (n = 7), idiopathic intracranial hypertension (n = 4), neoplastic (n = 1), and posterior cortical atrophy (n = 1). Some patients had partial improvement with benzodiazepines (n = 6), lamotrigine (n = 5), topiramate (n = 3) and acetazolamide (n = 3). Presenting characteristics were similar, but patients with visual snow attributed to an inciting event or contributing comorbidity were more likely to have some improvement in their symptoms by last follow-up compared to spontaneous visual snow ( p < .001). Conclusions Though most cases of visual snow are spontaneous, potential secondary causes should be recognized by clinicians. Patients who develop visual snow after an inciting event or related to an underlying comorbidity may have a better prognosis than those in whom it develops spontaneously. In select cases, treatment of the suspected underlying cause may significantly alleviate the otherwise typical intractable visual disturbances associated with visual snow.

Download Full-text

COGNITIVE MEASURE MAY IDENTIFY ATROPHY IN BRAIN REGIONS ASSOCIATED WITH POSTERIOR CORTICAL ATROPHY

Innovation in Aging ◽

10.1093/geroni/igx004.2060 ◽

2017 ◽

Vol 1 (suppl_1) ◽

pp. 587-587

Author(s):

E. Couser ◽

M. Albert ◽

C. Pettigrew ◽

A. Soldan

Keyword(s):

Brain Regions ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Cognitive Measure

Download Full-text

Tau filaments from multiple cases of sporadic and inherited Alzheimer’s disease adopt a common fold

10.1101/411215 ◽

2018 ◽

Author(s):

Benjamin Falcon ◽

Wenjuan Zhang ◽

Manuel Schweighauser ◽

Alexey G. Murzin ◽

Ruben Vidal ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Frontal Cortex ◽

Paired Helical Filaments ◽

Brain Regions ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Negative Stain ◽

Negative Stain Electron Microscopy ◽

Ordered Assembly

AbstractThe ordered assembly of tau protein into abnormal filaments is a defining characteristic of Alzheimer’s disease (AD) and other neurodegenerative disorders. It is not known if the structures of tau filaments vary within, or between, the brains of individuals with AD. We used a combination of electron cryo-microscopy (cryo-EM) and immuno-gold negative-stain electron microscopy (immuno-EM) to determine the structures of paired helical filaments (PHFs) and straight filaments (SFs) from the frontal cortex of 17 cases of typical AD (15 sporadic and 2 inherited) and 2 cases of atypical AD (posterior cortical atrophy). The high-resolution structures of PHFs and SFs from the frontal cortex of 3 cases of typical AD, 2 sporadic and 1 inherited, were determined by cryo-EM. We also used immuno-EM to study the PHFs and SFs from a number of cortical and subcortical brain regions. PHFs outnumbered SFs in all AD cases. By cryo-EM, PHFs and SFs were made of two C-shaped protofilaments with a combined cross-β/β-helix structure, as described previously for a case of AD. The higher resolution structures obtained here showed two additional amino acids at each end of the protofilament structure. The immuno-EM findings, which established the presence of repeats 3 and 4, but not repeats 1 and 2, of tau in the filament cores of all AD cases and brain regions thereof, were consistent with the cryo-EM results. These findings show that there is no significant variation in tau filament structures between individuals with AD. This knowledge will be crucial for understanding the mechanisms that underlie tau filament formation and for developing novel diagnostics and therapies.

Download Full-text

In vivo demonstration of amyloid burden in posterior cortical atrophy: a case series with PET and CSF findings

Journal of Neurology ◽

10.1007/s00415-011-6030-0 ◽

2011 ◽

Vol 258 (10) ◽

pp. 1841-1851 ◽

Cited By ~ 42

Author(s):

Maïté Formaglio ◽

Nicolas Costes ◽

Jérémie Seguin ◽

Yannick Tholance ◽

Didier Bars ◽

...

Keyword(s):

Case Series ◽

Cortical Atrophy ◽

Amyloid Burden ◽

Posterior Cortical Atrophy ◽

Csf Findings

Download Full-text

Phonological Errors in Posterior Cortical Atrophy

Dementia and Geriatric Cognitive Disorders ◽

10.1159/000516481 ◽

2021 ◽

pp. 1-9

Author(s):

Katerina A. Tetzloff ◽

Joseph R. Duffy ◽

Edythe A. Strand ◽

Mary M. Machulda ◽

Christopher G. Schwarz ◽

...

Keyword(s):

Clinical Symptoms ◽

Primary Progressive Aphasia ◽

Brain Regions ◽

Cortical Atrophy ◽

Posterior Cortical Atrophy ◽

Boston Naming Test ◽

Language Tests ◽

Language Difficulties ◽

Phonological Errors ◽

Gray Matter Volumes

Background: Posterior cortical atrophy (PCA) is an atypical variant of Alzheimer’s disease (AD) that presents with visuospatial/perceptual deficits. PCA is characterized by atrophy in posterior brain regions, which overlaps with atrophy occurring in logopenic variant of primary progressive aphasia (lvPPA), another atypical AD variant characterized by language difficulties, including phonological errors. Language abnormalities have been observed in PCA, although the prevalence of phonological errors is unknown. We aimed to compare the frequency and severity of phonological errors in PCA and lvPPA and determine the neuroanatomical correlates of phonological errors and language abnormalities in PCA. Methods: The presence and number of phonological errors were recorded during the Boston Naming Test and Western Aphasia Battery repetition subtest in 27 PCA patients and 27 age- and disease duration-matched lvPPA patients. Number of phonological errors and scores from language tests were correlated with regional gray matter volumes using Spearman correlations. Results: Phonological errors were evident in 55% of PCA patients and 70% of lvPPA patients, with lvPPA having higher average number of errors. Phonological errors in PCA correlated with decreased left inferior parietal and lateral temporal volume. Naming and fluency were also associated with decreased left lateral temporal lobe volume. Conclusions: Phonological errors are common in PCA, although they are not as prevalent or severe as in lvPPA, and they are related to involvement of left temporoparietal cortex. This highlights the broad spectrum of clinical symptoms associated with AD and overlap between PCA and lvPPA.

Download Full-text

Inefficient Encoding as an Explanation for Age-Related Deficits in Recollection-Based Processing

Journal of Psychophysiology ◽

10.1027/0269-8803/a000122 ◽

2014 ◽

Vol 28 (3) ◽

pp. 148-161 ◽

Cited By ~ 12

Author(s):

David Friedman ◽

Ray Johnson

Keyword(s):

Older Adults ◽

Young Adults ◽

Cognitive Processes ◽

Brain Activity ◽

Memory Performance ◽

Brain Regions ◽

Semantic Retrieval ◽

Age Related ◽

The Face ◽

Episodic Memories

A cardinal feature of aging is a decline in episodic memory (EM). Nevertheless, there is evidence that some older adults may be able to “compensate” for failures in recollection-based processing by recruiting brain regions and cognitive processes not normally recruited by the young. We review the evidence suggesting that age-related declines in EM performance and recollection-related brain activity (left-parietal EM effect; LPEM) are due to altered processing at encoding. We describe results from our laboratory on differences in encoding- and retrieval-related activity between young and older adults. We then show that, relative to the young, in older adults brain activity at encoding is reduced over a brain region believed to be crucial for successful semantic elaboration in a 400–1,400-ms interval (left inferior prefrontal cortex, LIPFC; Johnson, Nessler, & Friedman, 2013 ; Nessler, Friedman, Johnson, & Bersick, 2007 ; Nessler, Johnson, Bersick, & Friedman, 2006 ). This reduced brain activity is associated with diminished subsequent recognition-memory performance and the LPEM at retrieval. We provide evidence for this premise by demonstrating that disrupting encoding-related processes during this 400–1,400-ms interval in young adults affords causal support for the hypothesis that the reduction over LIPFC during encoding produces the hallmarks of an age-related EM deficit: normal semantic retrieval at encoding, reduced subsequent episodic recognition accuracy, free recall, and the LPEM. Finally, we show that the reduced LPEM in young adults is associated with “additional” brain activity over similar brain areas as those activated when older adults show deficient retrieval. Hence, rather than supporting the compensation hypothesis, these data are more consistent with the scaffolding hypothesis, in which the recruitment of additional cognitive processes is an adaptive response across the life span in the face of momentary increases in task demand due to poorly-encoded episodic memories.

Download Full-text