Recognising the self Flashcards
What are the positive symptoms of psychosis presented in the ICD-10?
- Delusions
- Auditory hallucinations
- Abnormalities of behaviour
- catatonia
- overexcitement
- retardation
What are auditory hallucinations observed in psychosis?
‘perceptions in the absence of external stimuli’
- usually derogatory (unpleasant) voices
What is the prevalence of auditory hallucinations in patients with schizophrenia?
60-70%
What is the prevalence of patients with schizophrenia that had made a suicide attempt in response to the voices they heard (Shergill, Murray and McGuire, 1998)?
25%
What are the two hypotheses (models) on the emergence of auditory hallucinations in schizophrenia?
- Like epilepsy, spontaneous firing of the brain over auditory cortex
- > hearing voices - In schizophrenia the awareness of our own thinking (often in words) is lost
- > thoughts that are experienced in one’s head without them tagged as one’s own
- > brain interprets them as external voice
What does the photic stimulation in an fMRI consist of?
- Statistical programme looking at brain activity over time
-> Which parts of the brain were more active during period when flashing the light
compared to period when there was darkness
- increased brain activation = primary visual cortex
What is the problem with fMRI machines when studying auditory hallucinations?
- High level of background noise -> confounding factor
- > different approach required to eliminate the background noise
What is the approach used with an MRI machine to study auditory hallucinations in the brain?
- Scanner off -> no noise
- Scanner on -> noise (2-3 secs): used as cue AND point in time where brain image is captured
- Rest (20-30 secs) at random: used to capture patient’s experience when lying in silence
- repeat multiple time (up to 60 or 100 times)
- Pick out times when hallucinations vs no hallucinations
- There’s a delay in the brain when looking at imaging signals
What do MRI scan results show about patients with auditory hallucinations (Shergill, Brammer, Williams, Murray and McGuire, 2000)?
Activation of auditory cortex AND inferior frontal gyrus (Broca’s area: speech and speaking) when patients are hearing voices
-> both speech generation AND speech hearing areas are active when patients are hearing voices
What is observed in MRI scan results of healthy controls when asked to generate some words (Shergill et al., 2001)?
Activation of inferior frontal gyrus, right homologous area AND auditory cortex
-> similar patterns of activation to patients suffering from auditory hallucinations
What is observed in MRI scan results when healthy controls are compared to patients prone to auditory hallucinations (whilst thinking in words) (Shergill et al., 2003)?
Less activation in people with schizophrenia compared to healthy controls
- in parahippocampal gyrus (responding to novel or unexpected words)
- in cerebellum (motor movements)
- in superior temporal gyrus (auditory processing and speech monitoring)
What do MRI scan results show on listening to external speech between healthy controls and patients prone to auditory hallucinations (Shergill et al., 2010)?
Hearing part of the brain is activated in similar way in patients and controls when listening to someone talking
What do MRI scan results show on the thinking in words between healthy controls and patients prone to auditory hallucinations (Shergill et al., 2010)?
Hearing part of the brain is switched off when thinking in words
- weaker in patients with schizophrenia
What does the study of Shergill and colleagues (2010) on the differences between patients with schizophrenia and healthy controls when listening to external speech and thinking in words?
Model for monitoring your own thinking doesn’t seem to be functioning as efficiently in patients with schizophrenia prone to auditory hallucinations
How is structural connectivity studied?
- Diffusion tensor technology
- White matter fibres that connect different parts of the brain
- Wherever two parts of brain are working together and regularly -> increase in white matter connections
- > examine white matter connections (structural differences)