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Bick A, McKyton A, Glick-Shames H, Rein N, Levin N. Abnormal network connections to early visual cortex in posterior cortical atrophy. J Neurol Sci 2023; 454:120826. [PMID: 37832379 DOI: 10.1016/j.jns.2023.120826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/15/2023]
Abstract
INTRODUCTION Posterior Cortical Atrophy (PCA), a visual variant of Alzheimer's disease, initially manifests with higher-order visual disorders and parieto/temporo-occipital atrophy. Recent studies have shown remote functional impairment in both distant brain networks and along the calcarine sulcus (V1). Functional alteration in the calcarine differs along its length, reflecting center to periphery visual space differences. Herein, we aim to connect between these two sets of findings by looking at the retinotopic patterns of functional connectivity between large-scale brain networks and V1, comparing patients with normally sighted subjects. METHODS Resting state functional magnetic resonance imaging (fMRI) and T1 anatomical scans were obtained from 11 PCA patients and 17 age-matched healthy volunteers. Default mode network (DMN) and fronto parietal network (FPN) were defined and differences between the networks in patients and healthy controls were evaluated at the whole brain level, specifically their connectivity to V1. RESULTS Connectivity patterns within the DMN and the FPN were similar between the groups, although differences were found in regions within and beyond the networks. Focusing on V1, in the control group we identified the expected pattern of a distributed connectivity along eccentricity, with foveal regions showing stronger connectivity to the FPN and peripheral regions showing stronger connectivity to the DMN. However, in PCA patients we could not identify a clear difference in connectivity along the eccentricities. CONCLUSION Lost specialization of function along the calcarine in PCA patients may have further implications on large-scale networks or vice versa. This impairment, distant from the core pathology, might explain patients' visual disabilities.
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Affiliation(s)
- Atira Bick
- fMRI unit, Neurology department, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Ayelet McKyton
- fMRI unit, Neurology department, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Haya Glick-Shames
- fMRI unit, Neurology department, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Netaniel Rein
- fMRI unit, Neurology department, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Israel
| | - Netta Levin
- fMRI unit, Neurology department, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Israel.
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Holden SK, Bettcher BM, Filley CM, Lopez-Paniagua D, Pelak VS. Posterior white matter integrity and self-reported posterior cortical symptoms using the Colorado Posterior Cortical Questionnaire. Front Neurol 2023; 14:1072938. [PMID: 36816576 PMCID: PMC9929951 DOI: 10.3389/fneur.2023.1072938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
Background The Colorado Posterior Cortical Questionnaire (CPC-Q) is a self-report, 15-item screening questionnaire for posterior cortical symptoms, including visuospatial and visuoperceptual difficulties. Changes in white matter connectivity may precede obvious gray matter atrophy in neurodegenerative conditions, especially posterior cortical atrophy. Integration of CPC-Q scores and measures of white matter integrity could contribute to earlier detection of posterior cortical syndromes. Methods We investigated the relationships between posterior cortical symptoms as captured by the CPC-Q and diffusion tensor imaging fractional anisotropy (DTI FA) of white matter regions of interest localized to posterior brain regions (posterior thalamic radiations, splenium of corpus callosum, tapetum). Comparisons were also made by diagnostic group [healthy older adult (n = 31), amnestic Alzheimer's disease (AD, n = 18), and posterior cortical atrophy (PCA, n = 9)] and by SENAS battery visuospatial composite score quartile. Exploratory comparisons of all available individual white matter region DTI FA to CPC-Q, as well as comparisons of DTI FA between diagnostic groups and visuospatial quartiles, were also made. Results CPC-Q score was correlated with the average DTI FA for the averaged posterior white matter regions of interest (r = -0.31, p = 0.02). Posterior thalamic radiation DTI FA was most strongly associated with CPC-Q (r = -0.34, p = 0.01) and visuospatial composite (r = 0.58, p < 0.01) scores and differed between the PCA and AD groups and the lower and higher visuospatial quartiles. The DTI FA of body and splenium of the corpus callosum also demonstrated this pattern but not the DTI FA of the tapetum. Conclusion The integrity of posterior white matter tracts is associated with scores on the CPC-Q, adding to the validation evidence for this new questionnaire. White matter regions that may be related to posterior cortical symptoms detected by the CPC-Q, and distinct from those affected in amnestic syndromes, include the posterior thalamic radiations and body and splenium of the corpus callosum. These findings are in line with previous neuroimaging studies of PCA and support continued research on white matter in posterior cortical dysfunction.
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Affiliation(s)
- Samantha K. Holden
- Department of Neurology, University of Colorado School of Medicine, Aurora, CO, United States,Department of Neurology, Behavioral Neurology Section, University of Colorado School of Medicine, Aurora, CO, United States,Department of Neurology, Movement Disorders Section, University of Colorado School of Medicine, Aurora, CO, United States,*Correspondence: Samantha K. Holden ✉
| | - Brianne M. Bettcher
- Department of Neurology, University of Colorado School of Medicine, Aurora, CO, United States,Department of Neurology, Behavioral Neurology Section, University of Colorado School of Medicine, Aurora, CO, United States
| | - Christopher M. Filley
- Department of Neurology, University of Colorado School of Medicine, Aurora, CO, United States,Department of Neurology, Behavioral Neurology Section, University of Colorado School of Medicine, Aurora, CO, United States,Department of Psychiatry, University of Colorado School of Medicine, Aurora, CO, United States,Marcus Institute for Brain Health, Aurora, CO, United States
| | - Dan Lopez-Paniagua
- Department of Radiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Victoria S. Pelak
- Department of Neurology, University of Colorado School of Medicine, Aurora, CO, United States,Department of Neurology, Behavioral Neurology Section, University of Colorado School of Medicine, Aurora, CO, United States,Department of Ophthalmology, University of Colorado School of Medicine, Aurora, CO, United States
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Pini L, Wennberg AM, Salvalaggio A, Vallesi A, Pievani M, Corbetta M. Breakdown of specific functional brain networks in clinical variants of Alzheimer's disease. Ageing Res Rev 2021; 72:101482. [PMID: 34606986 DOI: 10.1016/j.arr.2021.101482] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/24/2021] [Accepted: 09/29/2021] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is characterized by different clinical entities. Although AD phenotypes share a common molecular substrate (i.e., amyloid beta and tau accumulation), several clinicopathological differences exist. Brain functional networks might provide a macro-scale scaffolding to explain this heterogeneity. In this review, we summarize the evidence linking different large-scale functional network abnormalities to distinct AD phenotypes. Specifically, executive deficits in early-onset AD link with the dysfunction of networks that support sustained attention and executive functions. Posterior cortical atrophy relates to the breakdown of visual and dorsal attentional circuits, while the primary progressive aphasia variant of AD may be associated with the dysfunction of the left-lateralized language network. Additionally, network abnormalities might provide in vivo signatures for distinguishing proteinopathies that mimic AD, such as TAR DNA binding protein 43 related pathologies. These network differences vis-a-vis clinical syndromes are more evident in the earliest stage of AD. Finally, we discuss how these findings might pave the way for new tailored interventions targeting the most vulnerable brain circuit at the optimal time window to maximize clinical benefits.
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Mendez MF, Khattab YI, Yerstein O. Impaired visual search in posterior cortical atrophy vs. typical Alzheimer's disease. J Neurol Sci 2021; 428:117574. [PMID: 34271285 DOI: 10.1016/j.jns.2021.117574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/05/2021] [Accepted: 07/08/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Posterior cortical atrophy (PCA) is a neurocognitive disorder characterized by difficulty localizing in space. Recognizing PCA is important because it is usually missed early in its course and may result from a number of neurological disorders other than Alzheimer's disease (AD). OBJECTIVE This study aimed to clarify whether impaired visual search tasks of spatial localization distinguished patients with PCA from those with other more typical dementias as well as from healthy control (HC) subjects. METHODS Twelve patients meeting neuroimaging-supported Consensus Criteria for PCA, 12 comparably advanced patients with amnestic-predominant typical AD (tAD), and 24 HC participants were compared on tests of untimed and timed visual search, spatial neglect, mental rotation, environmental orientation, visuospatial construction, and face recognition. RESULTS Only abnormalities in untimed and timed visual search and environmental orientation distinguished the PCA patients from both the tAD group and the HC group without also distinguishing the tAD patients from HC's. The PCA patients also had a tendency to greater difficulty scanning left hemispace compared to HC's. Visuospatial constructions, although worse in PCA, and face recognition were impaired in both dementia groups. CONCLUSIONS These findings support the concept of PCA as a disorder of spatial processing and localization, indicating that visual search tasks are particularly sensitive and specific for detecting PCA and distinguishing it from more typical dementia syndromes.
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Affiliation(s)
- Mario F Mendez
- Departments of Neurology, David Geffen School of Medicine, University of California Los Angeles (UCLA), USA; Psychiatry and Behavioral Sciences, David Geffen School of Medicine, University of California Los Angeles (UCLA), USA; Neurology Service, Neurobehavior Unit, V.A. Greater Los Angeles Healthcare System, USA.
| | - Youssef I Khattab
- Departments of Neurology, David Geffen School of Medicine, University of California Los Angeles (UCLA), USA
| | - Oleg Yerstein
- Department of Neurology, Lahey Hospital and Medical Center, USA.
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Yerstein O, Parand L, Liang LJ, Isaac A, Mendez MF. Benson's Disease or Posterior Cortical Atrophy, Revisited. J Alzheimers Dis 2021; 82:493-502. [PMID: 34057092 PMCID: PMC8316293 DOI: 10.3233/jad-210368] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND D. Frank Benson and colleagues first described the clinical and neuropathological features of posterior cortical atrophy (PCA) from patients in the UCLA Neurobehavior Program. OBJECTIVE We reviewed the Program's subsequent clinical experience with PCA, and its potential for clarifying this relatively rare syndrome in comparison to the accumulated literature on PCA. METHODS Using the original criteria derived from this clinic, 65 patients with neuroimaging-supported PCA were diagnosed between 1995 and 2020. RESULTS On presentation, most had visual localization complaints and related visuospatial symptoms, but nearly half had memory complaints followed by symptoms of depression. Neurobehavioral testing showed predominant difficulty with visuospatial constructions, Gerstmann's syndrome, and Balint's syndrome, but also impaired memory and naming. On retrospective application of the current Consensus Criteria for PCA, 59 (91%) met PCA criteria with a modification allowing for "significantly greater visuospatial over memory and naming deficits." There were 37 deaths (56.9%) with the median overall survival of 10.3 years (95% CI: 9.6-13.6 years), consistent with a slow neurodegenerative disorder in most patients. CONCLUSION Together, these findings recommend modifying the PCA criteria for "relatively spared" memory, language, and behavior to include secondary memory and naming difficulty and depression, with increased emphasis on the presence of Gerstmann's and Balint's syndromes.
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Affiliation(s)
- Oleg Yerstein
- Department of Neurology, Lahey Hospital and Medical Center, Burlington, MA, USA
| | - Leila Parand
- Department of Neurology, Behavioral Sciences, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA
- Neurology Service, Neurobehavior Unit, V.A. Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Li-Jung Liang
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA
| | - Adrienne Isaac
- Department of Linguistics, Georgetown University, Washington, DC, USA
| | - Mario F. Mendez
- Department of Neurology, Behavioral Sciences, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA
- Neurology Service, Neurobehavior Unit, V.A. Greater Los Angeles Healthcare System, Los Angeles, CA, USA
- Department of Psychiatry and Behavioral Sciences, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA
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de Best PB, Abulafia R, McKyton A, Levin N. Convergence Along the Visual Hierarchy Is Altered in Posterior Cortical Atrophy. Invest Ophthalmol Vis Sci 2020; 61:8. [PMID: 32897377 PMCID: PMC7488212 DOI: 10.1167/iovs.61.11.8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 08/17/2020] [Indexed: 12/14/2022] Open
Abstract
Purpose Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome manifesting with visuospatial processing impairment. We recently suggested that abnormal population receptive field properties are associated with the symptoms of PCA patients. Specifically, simultanagnosia, the inability to perceive multiple items simultaneously, can be explained by smaller peripheral population receptive fields, and foveal crowding, in which nearby distractors interfere with object perception, may result from larger foveal population receptive fields. These effects occurred predominantly in V1, even though atrophy mainly involves high-order areas. In this study, we used connective field modeling to better understand these inter-area interactions. Methods We used functional magnetic resonance imaging to scan six PCA patients and eight controls while they viewed drifting bar stimuli. Resting-state data were also collected. Connective field modeling was applied for both conditions: once when the source was V1 and the targets were extrastriate areas and once for the opposite direction. The difference between the two was defined as convergence magnitude. Results With stimulus, the convergence magnitude of the controls increased along the visual pathway, suggesting that spatial integration from V1 becomes larger up the visual hierarchy. No such slope was found in the PCA patients. The difference between the groups originated mainly from the dorsal pathway. Without stimulus, the convergence magnitude was negative, slightly more so for the PCA patients, with no slope, suggesting constant divergence along the visual hierarchy. Conclusions Atrophy in one part of the visual system can affect other areas within the network through complex intervisual area interactions, resulting in modulation of population receptive field properties and an ensemble of visuocognitive function impairments.
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Affiliation(s)
- Pieter B. de Best
- fMRI Unit, Neurology Department, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ruth Abulafia
- fMRI Unit, Neurology Department, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ayelet McKyton
- fMRI Unit, Neurology Department, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Netta Levin
- fMRI Unit, Neurology Department, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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