Doctoral Dissertations

Date of Award

5-2010

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Psychology

Major Professor

Michael R. Nash

Committee Members

Daniela Corbetta, John H. Dougherty, Greg Reynolds

Abstract

Disorders of consciousness (DOC) occur in severe cases of neurological disease and acquired brain injury, spanning the continuum from complete unresponsiveness (vegetative state) to partial conscious awareness with only erratic voluntary behavioral responses (minimally conscious state). Assessing the patient’s level of awareness of self and their environment through behavioral evaluation is notoriously difficult and may lead to misdiagnosis if residual cognitive function goes undetected. A number of studies (Di et al., 2007; Staffen et al., 2008; Coleman et al., 2007; Qin et al., 2010) applying brain-imaging methods to measure brain activity associated with processing self-referential stimuli (stimuli related to the self) have found similar responses between patients with DOC and healthy volunteers. The present study involved a unique pediatric patient with comorbid quadriplegia and non-communicative impaired awaress who underwent fMRI to explore brain activity associated with the auditory presentation of personally relevant language stimuli: the subject’s own name (SON) and a familiar voice (FV). Activation was observed in the left tranverse temporal gyrus across all auditory stimuli. Presentation of the SON revealed activation in the left ventromedial prefrontal cortex (vMPFC) and right dorsolateral prefrontal cortex (DLPFC) and presentation of the FV revealed activation in the left supramarginal gyrus. These findings provide evidence of preserved brain activity in this patient during the presentation of self-referential stimuli and therefore support the application of functional neuroimaging methods to detect residual brain activity in pediatric patients who display impaired awareness.

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