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Title: Cerebral connectivity in psychosis
Author: Simmonite, Molly
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2013
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The central pathological process underlying schizophrenia remains unknown. During recent decades evidence from MRI studies investigating the integrity of distributed networks and EEG studies examining the recruitment of diverse brain regions has converged to support impaired coordination of brain regions as the pathological process of schizophrenia. This impaired coordination is often described as a disturbance of cerebral connectivity. However, a number of issues remain unresolved, regarding the heritability, mechanism and specificity of impaired coordination. This work uses both EEG techniques and fMRI to address these questions. In particular, EEG features previously reported in established illness were examined in tmaffected first-degree relatives, with the goal of assessing the extent to which coordination disturbances are present in those with genetic vulnerability for the ilh1ess. The main findings are reduced error related negativity (ERN) amplitudes and attenuated event-related low-frequency oscillations in unaffected siblings of patients with schizophrenia, indicating these abnormalities are not purely an expression of illness. The examination of cross frequency coupling in schizophrenia provides evidence for an abnormal hierarchy of oscillations, including reduced low frequency phase modulation of high frequency amplitude. This supports the hypothesis that the mechanism of impaired recruitment of distributed brain networks in schizophrenia is an attenuation of cross frequency coupling. The reported fMRI investigations demonstrated that, disturbances of the salience network, thought to govern the switch between states of brain connectivity, occur in both schizophrenia and bipolar disorder. The presence of abnormalities in patients with bipolar disorder that are similar in nature, yet less severe in comparison with those found in patients with schizophrenia supports the idea of a continuum of psychotic illness. Additionally relationships are present between functional connectivity measures of brain networks and the dimension of impairment, which is a cardinal feature of Kraepelin's concept of schizophrenia but is also found to a lesser degree in bipolar disorder.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available