The effect of parietal lobe lesions on symbolic and non-symbolic number representation and neuropsychological profiles

• Main Author: Khan, S. S.
• Published: University College London (University of London) 2010
• Subjects: 616.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625411

Part 1, the systematic literature review, examines the empirical literature on symbolic and non-symbolic number representation in humans. A diverse range of experimental methodologies were explored, including 19 studies which comprised computational modelling, neuroimaging, behavioural and clinical evidence, and 15 review articles which focused on the acquisition of number competence and the underlying form of number representation. The review revealed a lack of evidence on the qualitative differences between representations of symbolic and non-symbolic numbers, and hardly any clinical evidence of the underlying pathways. Part 2, the empirical paper, reports a study adapted from Roggeman, Verguts and Fias (2007), which used healthy participants, by using patients with lesions to the parietal lobe, an area commonly associated with numbers. We aimed to determine whether there were differences between symbolic and non-symbolic notations from which differences in underlying representations and areas engaged in the processing of these notations could be inferred. The priming task provided a measurable indicator of any differences between notations and the impact of these lesions on the ability to identify numbers presented as digits and dots. There were no significant differences in digit and dot notations between the patient and control groups. However, two case studies revealed normal digit and dot number representation following a left lesion, whereas normal digit and abnormal dot number representation was observed following a right lesion, thereby supporting a notation-dependent view. Part 3, the critical appraisal, provides a reflective discussion of the project from start to finish, addressing methodological choices, the clinical and research duality and wider conceptual issues.