scholarly journals Evaluating the granularity and statistical structure of lesions and behaviour in post-stroke aphasia

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Ying Zhao ◽  
Ajay D Halai ◽  
Matthew A Lambon Ralph
Keyword(s):  
Principal Component Analysis ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Principal Component ◽  
Component Analysis ◽  
Vascular Supply ◽  
Angular Gyrus ◽  
Statistical Structure ◽  
Speech Fluency ◽  
Post Stroke

Abstract The pursuit of relating the location of neural damage to the pattern of acquired language and general cognitive deficits post-stroke stems back to the 19th century behavioural neurology. While spatial specificity has improved dramatically over time, from the large areas of damage specified by post-mortem investigation to the millimetre precision of modern MRI, there is an underlying issue that is rarely addressed, which relates to the fact that damage to a given area of the brain is not random but constrained by the brain’s vasculature. Accordingly, the aim of this study was to uncover the statistical structure underlying the lesion profile in chronic aphasia post-stroke. By applying varimax-rotated principal component analysis to the lesions of 70 patients with chronic post-stroke aphasia, we identified 17 interpretable clusters, largely reflecting the vascular supply of middle cerebral artery sub-branches and other sources of individual variation in vascular supply as shown in classical angiography studies. This vascular parcellation produced smaller displacement error in simulated lesion–symptom analysis compared with individual voxels and Brodmann regions. A second principal component analysis of the patients’ detailed neuropsychological data revealed a four-factor solution reflecting phonological, semantic, executive-demand and speech fluency abilities. As a preliminary exploration, stepwise regression was used to relate behavioural factor scores to the lesion principal components. Phonological ability was related to two components, which covered the posterior temporal region including the posterior segment of the arcuate fasciculus, and the inferior frontal gyrus. Three components were linked to semantic ability and were located in the white matter underlying the anterior temporal lobe, the supramarginal gyrus and angular gyrus. Executive-demand related to two components covering the dorsal edge of the middle cerebral artery territory, while speech fluency was linked to two components that were located in the middle frontal gyrus, precentral gyrus and subcortical regions (putamen and thalamus). Future studies can explore in formal terms the utility of these principal component analysis-derived lesion components for relating post-stroke lesions and symptoms.

scholarly journals Evaluating the granularity and statistical structure of lesions and behaviour in post-stroke aphasia

2019 ◽  
Author(s):  
Ying Zhao ◽  
Ajay D. Halai ◽  
Matthew A. Lambon Ralph
Keyword(s):  
Principal Component Analysis ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Principal Component ◽  
Component Analysis ◽  
Vascular Supply ◽  
Angular Gyrus ◽  
Statistical Structure ◽  
Speech Fluency ◽  
Post Stroke

AbstractThe pursuit of relating the location of neural damage to the pattern of acquired language and general cognitive deficits post-stroke stems back to 19th century behavioural neurology. Whilst spatial specificity has improved dramatically over time, from the large areas of damage specified by post-mortem investigation to the millimetre precision of modern MRI, there is an underlying issue that is rarely addressed, which relates to the fact that damage to a given area of the brain is not random but constrained by the brain’s vasculature. Accordingly, the aim of this study was to uncover the statistical structure underlying the lesion profile in chronic aphasia post-stroke. By applying varimax-rotated principal component analysis to the lesions of 70 patients with chronic post-stroke aphasia, we identified 17 interpretable clusters, largely reflecting the vascular supply of middle cerebral artery sub-branches and other sources of individual variation in vascular supply as shown in classical angiography studies. This vascular parcellation produced smaller displacement error in simulated lesion-symptom analysis compared with individual voxels and Brodmann regions. A second principal component analysis of the patients’ detailed neuropsychological data revealed a four factor solution reflecting phonological, semantic, executive-demand and speech fluency abilities. As a preliminary exploration, stepwise regression was used to relate behavioural factor scores to the lesion principal components. Phonological ability was related to two components, which covered the posterior temporal region including the posterior segment of the arcuate fasciculus, and the inferior frontal gyrus. Three components were linked to semantic ability and were located in the white matter underlying the anterior temporal lobe, the supramarginal gyrus and angular gyrus. Executive-demand related to two components covering the dorsal edge of the middle cerebral artery territory, while speech fluency was linked to two components that were located in the middle frontal gyrus, precentral gyrus, and subcortical regions (putamen and thalamus). Future studies can explore in formal terms the utility of these PCA-derived lesion components for relating post-stroke lesions and symptoms.

scholarly journals A new methodology based on functional principal component analysis to study postural stability post-stroke

2018 ◽  
Vol 56 ◽  
pp. 18-26 ◽  
Author(s):  
M. Luz Sánchez-Sánchez ◽  
Juan-Manuel Belda-Lois ◽  
Silvia Mena-del Horno ◽  
Enrique Viosca-Herrero ◽  
Celedonia Igual-Camacho ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Postural Stability ◽  
Principal Component ◽  
Component Analysis ◽  
Functional Principal Component Analysis ◽  
Post Stroke ◽  
Functional Principal Component

scholarly journals EFECTOS DE LA ESTRUCTURA ESTADÍSTICA DE LOS DATOS EN LA IMPLEMENTACIÓN DE LA RED NEURONAL AUTOSUPERVISADA

2017 ◽  
Vol 23 (1) ◽  
pp. 67
Author(s):  
Luis E. Huamanchumo de la Cuba ◽  
Luis A. Sánchez Alvarado
Keyword(s):  
Neural Network ◽  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Statistical Structure ◽  
Predictive Capacity ◽  
Technical Aspects ◽  
Palabras Clave ◽  
La Red

La presente investigación plantea como objetivo estudiar aspectos técnicos relacionados con la implementación de la red neuronal de Análisis de Componentes Principales (ACP) en términos de su capacidad predictiva, generalización y precisión con el fin de establecer criterios óptimos para su validación, evaluación del desempeño e implementación. Para ello, se plantea la hipótesis de que la estructura estadística de los datos influye significativamente en el óptimo desempeño de la red neuronal de ACP en el contexto no supervisado. Se demostró que el algoritmo Hebbiano de la fase de aprendizaje garantiza la calidad de representación de la red debido a que capitaliza eficientemente la información en escenarios con varianza generalizada grande. Palabras clave.-Análisis de componentes principales, Algoritmo hebbiano, Reducción de dimensionalidad. ABSTRACTThe purpose of this research is to study technical aspects involved in the implementation of a Principal Component Analysis (PCA) neural network in terms of predictive capacity, generalization and accuracy in order to establish optimal criteria for the validation and implementation thereof. Our hypothesis is that the statistical structure of the data affects the optimal performance of a PCA neural network in the unsupervised context. It was demonstrated that the Hebbian algorithm at the learning phase ensures enhanced quality of network representation as it makes efficient use of information where generalized variance is large. Keywords.-Principal component analysis, Hebbian algorithm, Dimensionality reduction

scholarly journals Graded, multidimensional intra- and intergroup variations in primary progressive aphasia and post-stroke aphasia

Brain ◽  
2020 ◽  
Vol 143 (10) ◽  
pp. 3121-3135 ◽  
Author(s):  
Ruth U Ingram ◽  
Ajay D Halai ◽  
Gorana Pobric ◽  
Seyed Sajjadi ◽  
Karalyn Patterson ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Diagnostic Category ◽  
Principal Component ◽  
Primary Progressive Aphasia ◽  
Component Analysis ◽  
Underlying Structure ◽  
Progressive Aphasia ◽  
Primary Progressive ◽  
Post Stroke ◽  
Group Homogeneity

Abstract Language impairments caused by stroke (post-stroke aphasia, PSA) and neurodegeneration (primary progressive aphasia, PPA) have overlapping symptomatology, nomenclature and are classically divided into categorical subtypes. Surprisingly, PPA and PSA have rarely been directly compared in detail. Rather, previous studies have compared certain subtypes (e.g. semantic variants) or have focused on a specific cognitive/linguistic task (e.g. reading). This study assessed a large range of linguistic and cognitive tasks across the full spectra of PSA and PPA. We applied varimax-rotated principal component analysis to explore the underlying structure of the variance in the assessment scores. Similar phonological, semantic and fluency-related components were found for PSA and PPA. A combined principal component analysis across the two aetiologies revealed graded intra- and intergroup variations on all four extracted components. Classification analysis was used to test, formally, whether there were any categorical boundaries for any subtypes of PPA or PSA. Semantic dementia formed a true diagnostic category (i.e. within group homogeneity and distinct between-group differences), whereas there was considerable overlap and graded variations within and between other subtypes of PPA and PSA. These results suggest that (i) a multidimensional rather than categorical classification system may be a better conceptualization of aphasia from both causes; and (ii) despite the very different types of pathology, these broad classes of aphasia have considerable features in common.

scholarly journals Graded, multi-dimensional intragroup and intergroup variations in primary progressive aphasia and post-stroke aphasia

2019 ◽  
Author(s):  
Ruth U. Ingram ◽  
Ajay D. Halai ◽  
Gorana Pobric ◽  
Seyed Sajjadi ◽  
Karalyn Patterson ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Diagnostic Category ◽  
Principal Component ◽  
Primary Progressive Aphasia ◽  
Component Analysis ◽  
Underlying Structure ◽  
Progressive Aphasia ◽  
Primary Progressive ◽  
Post Stroke ◽  
Group Homogeneity

AbstractLanguage impairments caused by stroke (post-stroke aphasia) and neurodegeneration (primary progressive aphasia) have overlapping symptomatology, nomenclature and are classically divided into categorical subtypes. Surprisingly, primary progressive aphasia (PPA) and post-stroke aphasia (PSA) have rarely been directly compared in detail. Rather previous studies have compared certain subtypes (e.g., semantic variants) or have focussed on a specific cognitive/linguistic task (e.g., reading). This study assessed a large range of linguistic and cognitive tasks across the full spectra of PSA and PPA. We applied varimax-rotated principal component analysis to explore the underlying structure of the variance in the assessment scores. Similar phonological, semantic and fluency-related components were found for PSA and PPA. A combined principal component analysis across the two aetiologies revealed graded intragroup and intergroup variations on all four extracted components. Classification analysis was employed to test, formally, whether there were any categorical boundaries for any subtypes of PPA or PSA. Semantic dementia proved to form a true diagnostic category (i.e., within group homogeneity and distinct between group differences), whereas there was considerable overlap and graded variations within and between other subtypes of PPA and PSA. These results suggest that (a) a multi-dimensional rather than categorical classification system may be a better conceptualisation of aphasia from both causes, and (b) despite the very different types of pathology, these broad classes of aphasia have considerable features in common.

A German version of the Intermittent Claudication Questionnaire (ICQ): cultural adaptation and validation

VASA ◽  
2012 ◽  
Vol 41 (5) ◽  
pp. 333-342 ◽  
Author(s):  
Kirchberger ◽  
Finger ◽  
Müller-Bühl
Keyword(s):  
Principal Component Analysis ◽  
Intermittent Claudication ◽  
Completion Time ◽  
Short Form ◽  
Principal Component ◽  
Component Analysis ◽  
German Version ◽  
Average Completion Time ◽  
Sf 36 ◽  
Related Quality

Background: The Intermittent Claudication Questionnaire (ICQ) is a short questionnaire for the assessment of health-related quality of life (HRQOL) in patients with intermittent claudication (IC). The objective of this study was to translate the ICQ into German and to investigate the psychometric properties of the German ICQ version in patients with IC. Patients and methods: The original English version was translated using a forward-backward method. The resulting German version was reviewed by the author of the original version and an experienced clinician. Finally, it was tested for clarity with 5 German patients with IC. A sample of 81 patients were administered the German ICQ. The sample consisted of 58.0 % male patients with a median age of 71 years and a median IC duration of 36 months. Test of feasibility included completeness of questionnaires, completion time, and ratings of clarity, length and relevance. Reliability was assessed through a retest in 13 patients at 14 days, and analysis of Cronbach’s alpha for internal consistency. Construct validity was investigated using principal component analysis. Concurrent validity was assessed by correlating the ICQ scores with the Short Form 36 Health Survey (SF-36) as well as clinical measures. Results: The ICQ was completely filled in by 73 subjects (90.1 %) with an average completion time of 6.3 minutes. Cronbach’s alpha coefficient reached 0.75. Intra-class correlation for test-retest reliability was r = 0.88. Principal component analysis resulted in a 3 factor solution. The first factor explained 51.5 of the total variation and all items had loadings of at least 0.65 on it. The ICQ was significantly associated with the SF-36 and treadmill-walking distances whereas no association was found for resting ABPI. Conclusions: The German version of the ICQ demonstrated good feasibility, satisfactory reliability and good validity. Responsiveness should be investigated in further validation studies.

Sign in / Sign up

Export Citation Format

Share Document