Monothematic Delusions - created from Mind Map

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Coltheart 2007

types of delusions

mirrored self misidentification

somatoparaphrenia

capgras

cotards

Fregoli

intermetamorphis

relates to strength of emotional connection to other agent - delusion occurs where connection is strongest

imposters

causes

33% associated with traumatic brain lesion/organic brain damage in the right hemisphere (Ramachandren 1998)

seen in schizophrenia and in 10% of alzheimer patients

Berson 1983

Ellis 1997

Hirstein 1997

disconnection hypothesis

can explain everything - your in heaven too

patients are disconnected from their sensory experience of the external world - world doesn't feel right

implicated right hemisphere and patients often depressed

Ramachandren 1998

Pure autonomic failure

rare, dysfunction of right hemisphere

Ellis and Young Dual route theory

if a strong autonomic response indicates a face is familiar to you, yet you do not recognise them, then assume they must be in disguise

the right hemisphere plays an important role in delusions

EXPLANATIONS

Dual model

Coltheart 2007 - one factor explanations are not enough

Maher

Coltheart 2010 - failure in TOM?

Ellis and Young 1990

two deficits: a) what causes the anomalous perception (autonomic failure) and b) a failure in belief evaluation failure that leads to the delusion being adopted

no deficit in reasoning - can be aware belief is weird. Deficit is in belief evaluation

Process of adductive inference

proposition goes through belief evaluation process - if fits with data must be true, delusion adopted!

delusions of familiarity in the normal population

deja vu

Jamais Vu

Neppe 1983

associated with temporal lobe epilepsy/lesions/tumours/psychopathology

indicates that states of heightened neurological activity must occur in the normal brain

Theories

related to pre seizure state (Harper 1969)

right hemisphere association

associated with diffuse electrical discharge in anterior temporal lobe (Halgren 1978)

medial temporal lobe (Gloor 1982)

Penfield 1955

Similarity to other contexts previously been in

double perception accounts

Dual processing (Gloor 1990)

small seizure in hippocampal regions or alteration in time course of neural transmission

two cognitive processes become uncoordinated

retrieval of info

familiarity of info

rare (Ardila 1993)

Penfield 1995 - relation to pre seizure aura

negative, cold and strange, similarity with capgras

no dominant explanatory theory

feeling of recall without familiarity

Schacter 1984 - source amnesia

the right hemisphere has more trouble inhibiting itself than the left hemisphere

right hemisphere - crucial for delusions - belief evaluation systems

Coltheart 2007 - if a true belief is held for no good reason is it a delusion? do delusions have to be beliefs? a belief held by an entire community could be a delusion.

mirrored self misidentification - do not recognise self in the mirror

denial of limb ownership

Capgras 1923 - the belief that people close to you have been replaced by impostors - recognise but don't feel familiarity. can be sustained or transient and variable

Cotards - belief that one is dead

Fregoli - being followed by close friends but they are in disguise - feeling of familiarity with no recognition

Berson 1983 - failure of affective component of the familiarity system. A delay in the attribution of familiarity may lead patient to falsely believe person is an imposter. can attribute familiarity but there is a delay which leads to the idea that something isn't right

Ellis and Young 1990 - dual route model. a disconnection between dorsal (affective response route) and ventral (conscious recognition) streams.

Damage to dorsal route leads to Capgras - can consciously recognise but no feelings of familiarity.

Capgras is the opposite of prosopagnosia where face recognition is impaired

Ellis 1997 - testsed 5 capgras, 5 age matched, 5 psychotic. presented with pictures of famous and non famous people and measured skin conduction as an index of autonomic processing of familiarity. there was no difference between the face categories for the people with Capgras suggesting they have a problem with autonomic processing.

Hirstein 1997 - measured SCRs in response to personally emotionally salient stimuli. Little or no change in SCR response in those with Capgras even when presented with picture of mother.

disconnection hypothesis - break in connection between the amygdala and inferotemporal cortex (face processing) - stimuli are recognised but are not associated with emotional feelings. Same idea as Ellis 1990 but different networks.

intermetamorphis - familiar friend or individual replaced by friend or relative

dual route and fregoli - affective system inappropriately activated leading to patient being highly responsive to faces - even unfamiliar ones.

fregoli is over activity in familiarity processing whereas capgras is suppression of this pathway

Ramachandren 1998 - sensory areas become disconnected from limbic structures which leads to flattened or complete loss of autonomic responsiveness. Patients believe they are no longer connected to the world and so must be death

Maher - thinking process rational - trying to explain an anomalous perception

pure autonomic failure - no emotional response to anything but no cotards

abductive inference = this happened therefore this must be why. explanation for what occurred. doesn't have to be correct.

déjà vu - familiarity for unfamiliar

jamais vu - unfamiliarity for familiar

deja and jamais vu opposite ends of same familiarity function

Neppe 1983 - any subjectively inappropriate impression of familiarity of a present experience with undefined past

Jackson 1888 - 73% of temporal lobe epileptics with deja vu had seizures originating in the right hemisphere. those with no deja vu had less hemispheric distinction. Also occurred under direct brain stimulation

Penfield 1955 - deep implanted electrode technology revealed a role for the hippocampus, amygdala, lateral temporal lobe

double perception accounts - perceives info subconsciously then later sees it consciously so feels familiarity for it

Gloor 1990 - dual processing in déjà vu - déjà vu is unintended conséquence of disruption of the two processes (retrieval and familiarity of info). four types of disruption: spontaneous activation of memory function, merging of 2 mnemonic functions, temporal delay between 2 functions, emergence of info into consciousness

Monothematic Delusions

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