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Nick Medford

4 papers in the library · 167 citations · publishing 2013-2018

Papers

Anomalous self-experience in depersonalization and schizophrenia: a comparative investigation.

Consciousness and Cognition June 1, 2013 Louis Sass, Elizabeth Pienkos, Barnaby Nelson et al. 144 citations

Anomalous self-experiences are central to schizophrenia and other psychiatric disorders. This analysis compared such experiences in schizophrenia-spectrum disorders, as cataloged in the EASE, with those described in severe depersonalization. Numerous affinities were found, showing that pure forms of diminished self-affection (depersonalization) can involve experiences resembling those of schizophrenia. However, important discrepancies emerged, suggesting that more automatic or deficiency-like factors—probably involving self/world or self/other confusion and erosion of first-person perspective—are more distinctive of schizophrenia-spectrum disorders.

Impairment of perceptual metacognitive accuracy and reduced prefrontal grey matter volume in first-episode psychosis

Cognitive Neuropsychiatry February 27, 2018 Geoff Davies, Charlotte L. Rae, Sarah N. Garfinkel et al. 23 citations

People in the early stages of psychosis show a reduced ability to accurately evaluate their own perceptions, a metacognitive deficit. In a perceptual decision-making task, individuals with first-episode psychosis performed worse on metacognitive accuracy than healthy controls, even when their basic perceptual performance was accounted for. Grey matter volume was also reduced in the superior frontal gyrus, a brain region linked to metacognition. However, no direct relationship was found between grey matter volume and metacognitive accuracy, leaving the neural basis of this deficit unclear. These findings suggest that a specific problem in scrutinizing one's own perceptions may underlie later functional difficulties in schizophrenia.

Emotional Experience and Awareness of Self: Functional MRI Studies of Depersonalization Disorder.

Frontiers in Psychology January 1, 2016 Nick Medford, Mauricio Sierra, Argyris Stringaris et al.

In depersonalization disorder (DPD), a condition marked by a diminished sense of self and dampened emotional experience, functional MRI revealed that emotional processing is altered. Before treatment, patients showed reduced brain activity in the insula—a region linked to interoceptive awareness and feeling states—along with attenuated autonomic responses to emotional visual stimuli. After pharmacological treatment, clinical improvement in DPD symptoms was associated with increased insula activity. A right ventrolateral prefrontal cortex area also appeared to be involved in top-down inhibition of emotional responses. These findings connect emotional numbing in DPD to disrupted interoception and self-related processes.

Fractionating the unitary notion of dissociation: disembodied but not embodied dissociative experiences are associated with exocentric perspective-taking.

Frontiers in Human Neuroscience January 1, 2013 Jason J Braithwaite, Kelly James, Hayley Dewe et al.

People who have had out-of-body experiences (OBEs) are more efficient at taking an external, third-person perspective on a novel perspective-taking task compared to people who have not had OBEs. They also report significantly higher levels of derealization—feeling alienated from their surroundings—but not higher levels of other anomalous body experiences, emotional numbing, or sensory recall anomalies. These results support a distinction between embodied dissociative experiences (like feeling unreal) and disembodied ones (like OBEs), with only the latter linked to enhanced exocentric perspective-taking. The findings suggest that OBEs may reflect a facilitated ability to adopt an external viewpoint, rather than a deficit.