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Functional hemispheric asymmetries in emotional processing and nosognosia


Tamagni, C. Functional hemispheric asymmetries in emotional processing and nosognosia. 2011, University of Zurich, Faculty of Medicine.

Abstract

Aim of the present doctoral thesis was to investigate how the human brain builds a positively biased picture one’s own health state. The first part of the section “own contributions” is dedicated to the study of positive illusions in the process of self-evaluation. The second part introduces two experiments on lateralized emotional processing, with a special focus on the influence of emotion on spatial attention. Anosognosia designates the inability to recognize one’s own illness. Representing one of the most striking and enigmatic forms of agnosia, no model is currently able to account fully and comprehensively for the phenomenon in its scope and complexity. Unlike previous investigations focusing on dysfunction, the present thesis emphasizes the study of the normal function impaired in anosognosia, a function reasonably labeled nosognosia. Nosognosia is the function that continuously monitors our own well-being, against the background of interoceptive and external changes. It comprises not only the detection of signs of illness, but also the ability to realistically estimate one's future health state. Many studies showed that the latter is generally biased towards optimism and that healthy people display a strong tendency to view themselves as less likely than others to turn ill. This positive illusion is called unrealistic optimism. We argue that there is a qualitative similarity between clinical confabulatory behavior and unrealistic optimism. Conceptualizing the optimistic attitude inherent to nosognosia as a form of “prospective anosognosia”, study 1 supports this view. In the same way it abolishes anosognosic denial, left-ear cold water irrigation reduced unrealistic optimism for one’s own future health state in healthy subjects. This finding indicates the right parieto-insular cortex – activated by this procedure - as a key structure for the appraisal of one’s own vulnerability to illness. Study 2 and 3 investigate brain lateralization of emotions, exploring the interaction between emotional processing and spatial attention. We found a modulation of spatial attention by emotional states and traits with a strong association between negative affect and leftward hemispatial attention. Our results validate the predominant role of the right hemisphere in negative emotions and indicate the importance of the parietal lobes in the processing of non-spatial contents. Together, the findings of the experiments with healthy volunteers are consistent with clinical observations from patients with unilateral brain lesions as well as with previous findings collected in healthy populations. They corroborate the existence of functional hemispheric asymmetries in both self-awareness and emotional processing and support the view of a right hemisphere specialization for both the ability to recognize one’s own illness and to process negative emotions.

Abstract

Aim of the present doctoral thesis was to investigate how the human brain builds a positively biased picture one’s own health state. The first part of the section “own contributions” is dedicated to the study of positive illusions in the process of self-evaluation. The second part introduces two experiments on lateralized emotional processing, with a special focus on the influence of emotion on spatial attention. Anosognosia designates the inability to recognize one’s own illness. Representing one of the most striking and enigmatic forms of agnosia, no model is currently able to account fully and comprehensively for the phenomenon in its scope and complexity. Unlike previous investigations focusing on dysfunction, the present thesis emphasizes the study of the normal function impaired in anosognosia, a function reasonably labeled nosognosia. Nosognosia is the function that continuously monitors our own well-being, against the background of interoceptive and external changes. It comprises not only the detection of signs of illness, but also the ability to realistically estimate one's future health state. Many studies showed that the latter is generally biased towards optimism and that healthy people display a strong tendency to view themselves as less likely than others to turn ill. This positive illusion is called unrealistic optimism. We argue that there is a qualitative similarity between clinical confabulatory behavior and unrealistic optimism. Conceptualizing the optimistic attitude inherent to nosognosia as a form of “prospective anosognosia”, study 1 supports this view. In the same way it abolishes anosognosic denial, left-ear cold water irrigation reduced unrealistic optimism for one’s own future health state in healthy subjects. This finding indicates the right parieto-insular cortex – activated by this procedure - as a key structure for the appraisal of one’s own vulnerability to illness. Study 2 and 3 investigate brain lateralization of emotions, exploring the interaction between emotional processing and spatial attention. We found a modulation of spatial attention by emotional states and traits with a strong association between negative affect and leftward hemispatial attention. Our results validate the predominant role of the right hemisphere in negative emotions and indicate the importance of the parietal lobes in the processing of non-spatial contents. Together, the findings of the experiments with healthy volunteers are consistent with clinical observations from patients with unilateral brain lesions as well as with previous findings collected in healthy populations. They corroborate the existence of functional hemispheric asymmetries in both self-awareness and emotional processing and support the view of a right hemisphere specialization for both the ability to recognize one’s own illness and to process negative emotions.

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Additional indexing

Item Type:Dissertation
Referees:Jäncke L, Brugger P
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neurology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2011
Deposited On:29 Feb 2012 07:47
Last Modified:05 Apr 2016 15:43
Related URLs:http://opac.nebis.ch/F/?local_base=NEBIS&CON_LNG=GER&func=find-b&find_code=SYS&request=006467471

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