The Neuropsychology of Stroke in the Back of the Brain: Clinical and Cognitive Aspects

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

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In this thesis, work from two research projects is presented. The first section concerns the Back of the Brain (BoB) project and the second concerns the Danish Oxford Cognitive Screen (OCS-Dansk) project.
Face recognition and word recognition have traditionally been thought to rely on highly specialised, largely lateralised and independent cognitive processes. More recently, it has been suggested, that face and word recognition are instead supported by common and highly overlapping networks that are more bilaterally distributed. The debate relies highly on findings from studies of patients selected according to their highly category-selective deficits. The BoB project takes a different approach and aims to shed new light on the processes and cerebral architecture underlying the visual recognition of complex stimuli such as faces, objects and words. A large group of patients (aim: N=70) recruited according to lesion localisation (posterior cerebral artery stroke) are tested with the same large battery of sensitive behavioural tests covering lower-level, intermediate and higher-level visual perceptual functions.
Reports of patients with pure prosopagnosia and pure alexia have been considered as key evidence in favour of the position that face recognition and reading rely on processes that are highly independent and lateralised. However, it has more recently been suggested that, if tested properly, all patients with prosopagnosia should have visual word processing deficits, and all patients with pure alexia should have face recognition deficits. In Article 1: Face And Word Recognition Can Be Selectively Affected By Brain Injury Or Developmental Disorders, studies investigating whether face and word recognition can be selectively affected by acquired brain injury or developmental disorders, are reviewed. It is concluded that there is strong evidence that reading can be preserved in acquired and developmental prosopagnosia, and also evidence, though weaker, that face recognition can be left unimpaired in acquired or developmental dyslexia.
When identifying associations and dissociations between face processing and reading abilities, the same levels of processing needs to be assessed across categories. There is an abundance of face processing tests available assessing different levels of processing, making test selection for studies challenging. In Article 2: Tests Of Whole Upright Face Processing In Prosopagnosia: A Literature Review, literature is reviewed to identify tests that have been used to assess the processing of whole upright faces in acquired and developmental prosopagnosia. This resulted in a visual overview of tests classified according to the level of processing that they assess (perception, recognition and identification), as well as their experimental design. The overview is particularly useful when selecting face processing tests for a studies that compare performance across visual categories.
Article 3: Similar incidences of visual face and word processing deficits in patients with left and right posterior stroke, concerns a study assessing face and word recognition deficits in 32 patients with unilateral left and 21 patients with unilateral right lesions, respectively. The incidence of face recognition deficits and word recognition deficits were similar following lesions in either hemisphere, suggesting that face and word recognition may be supported by processes that are more bilaterally distributed than previously assumed. There was stronger evidence for impaired word recognition with preserved face recognition than the opposite pattern, a findings that stands somewhat in contrast to findings from Article 1. Findings are discussed in the context of the Many-to-Many Hypothesis.
The OCS-Dansk project, that is presented in Article 4: A Danish Version Of The Oxford Cognitive Screen: A Stroke-Specific Screening Test Providing A Useful Alternative To Currently Used Tools, involves the collection of reference material for a Danish version of the Oxford Cognitive Screen (OCS). 91 neurotypical Danish-speaking controls were assessed with the OCS-Dansk as well as the Montreal Cognitive Assessment, and cut-offs were calculated for both tools. The study identified problems related to the MoCA cut-off currently used in Denmark, and concluded that the OCS may provide a useful alternative when screening for cognitive deficits in stroke patients in Denmark. Methodological considerations related to creating the normative material are discussed in the dissertation.
OriginalsprogEngelsk
Udgivelses stedCopenhagen
ForlagFaculty of Social Sciences, University of Copenhagen
Antal sider193
ISBN (Trykt)978-87-7209-234-8
StatusUdgivet - 7 jan. 2019

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