Delusion of agency, control and ownership

1. the brain doesn't automatically know the difference

1. Jeanerrod 2003 - mechanism by which own actions are distinguished from others is critical
2. delusions of agency = self monitoring errors
   1. self processing concepts

      Annotations:

      • self processing concepts:  action/agency/intention, autobiographical memory, self in imagery and memory, depersonalisation, language and self, social self
3. the self
   1. a set of ideas, beliefs, mental representations and models about who we are

      Annotations:

      • some representations of our self are explicit and available for conscious introspection - intentions, feelings, body image.  other representations are implicit - subconscious schemas which cannot be consciously inspected

1. mechanisms that tell you that you are the author of your own actions/intentions/thoughts
   1. to distinguish between self and other - self monitoring

      Annotations:

      • Szechtman 1998 - internal source monitoring system where inappropriate activation may be involved with internal thoughts being experienced as coming from an external source.  E.g. to be alien from self - lose sense of agency over thoughts/inner speech/intentions
2. the self and agency
   1. agency covers many factors

      Annotations:

      • agency covers many factors: thinking about action, intention to act, executing actions, receiving feedback.  these all draw on different underlying systems all of which can go wrong and lead to various forms of delusions.  acting is not a unitary phenomena - all aspects have separate neural substrates.  
3. Gallagher 2000
   1. need a sense of ownership and a sense of agency - being aware of action and being aware that they are responsible for acting

      Annotations:

      • reflex actions - action is beyond consciousness - no intention to move. sense of ownership and sense of agency usually coincide but can dissociate - dissociation can be caused by TMS.

1. alien control

   Annotations:

   • alien control - alien hand syndrome, thought control, thought insertion, thought withdrawal
   1. alien hand syndrome

      Annotations:

      • alien hand syndrome - see limbs move but it feels like it is being controlled by an alien force.  lose sense of intention to move but not ability. not always a transient phenomena
   2. symptoms associated with schizophrenia in which patients misattribute self generated actions to an external source (Blakemore 2003)

      Annotations:

      • Schizophrenia: thoughts/speech/actions influenced or replaced by those of external agents.  lost feeling of agency and ownership
   3. Schneider 1959 - first rank symptoms of schizophrenia
      1. Frith 2000 - experiences due to a lack of awareness of intended actions

         Annotations:

         • if intention is separated from action then it appears as though the action doesn't belong to you
2. passivity phenomena

   Annotations:

   • passivity phenomena - not in control of thoughts and actions - someone else is controlling
3. auditory hallucinations

1. everytime a saccade occurs, image on the retina changes dramatically
   1. yet we retain a stable image of the world
      1. Van Helmhotzl 1867

         Annotations:

         • Van Helmhotzl -  muscles invovled in moving the eye send a message to the brain which allows brain to compensate for the change and keep the image stable.  sends an efferent copy
      2. Van Hoist 1954

         Annotations:

         • Van Hoist 1954 - when sending motor commands to move the eye the motor areas of the brain send a parallel efference copy to visual areas.  this predicts sensory consequences (corollary discharge) of the movement which is used to compensate for retinal displacement during eye movements .  motor areas tell perceptual area that any disturbance is due to eye movement and not the world moving so compensation is made and we do not see the fragmented world shown on the retina.
      3. corollary discharge = the brain detects predicted sensory outcomes and compensates the resulting perception. sensory prediction

         Annotations:

         • corollary discharge notion has been applied to self produced actions and self monitoring.  Firth - we have an internal model of motor control that normally allows us to recognise the sensory consequences our actions

1. Miall 1993 - forward model of motor control
2. sensations from actions compared with internal mental model of action in order to establish agency
   1. if model matches action related sensory signals then action is attributed to the self
      1. if there is a discrepancy between sensory signals and model of predicted consequences then action is attributed to someone else
3. forward dynamic component
   1. makes predictions about the next state of the system and compares this with the desired state
      1. helps formulate action appropriate to intention
   2. forward output component
      1. predictions of sensory consequences of movement compared with actual sensory consequences of movement - needs access to efferent copy
4. the forward model and delusions of alien control
   1. discrepancy in comparison between predicted and actual sensory consequences cancel out reafferant inputs and be used to distinguish between self produced and externally produced signals.
   2. forward output model is impaired - cannot generate an accurate prediction if no access to efferent copy
      1. leads to large sensory discrepancy which leads to self produced action feeling as if it was externally produced
5. action you wanted performed, aware of intention but not aware of initiating action or aware of its predicted sensory consequences = fells as if actions are made by an external force
6. supporting evidence - why can't you tickle yourself?

   Annotations:

   • Blakemore 1998/1999/2000  why can't you tickle yourself? subjects rated sensation of a tactile stimulus and looked at the perceptual effects from altering the correspondence between self generated movement and sensory consequences.  employed delays between left arm movement and right arm stimulation.  as delay increased tactile stimuli perceived as more likely to feel like its someone else.  as discrepancy increases the efferent copy becomes inaccurate,  Blakemore 1999 - self produced sensation less intense than when produced by a robot. self generated action has predicted consequences and so the brain makes allowances for the consequences of the action.  externally generated actions cannot be attenuated as they are unexpected and therefore the movement feels more intense.  when the prediction of self generated movement is lost, then the actions are not attenuated and so feel like someone else produced them.
   1. Frith 2000

      Annotations:

      • frith 2000 - sensory discrepancy large in schizophrenics so own actions are always experienced as coming from an external source.  schizophrenics shouldn't show usual patterns with self tickling
      1. Blackmore 2000

         Annotations:

         • Blakemore 2000 - patient study of self monitoring.  looked at schizophrenics with and without passivity and hallucination and normal controls  asked to rate perception of a tactile sensation on left palm, sensation either self or externally produced.  perception not modulated by self generated actions in patients with hallucinations/passivity.  internally generated sensations rated as more intense therefore must be from an external source.  

1. Blakemore 2003

   Annotations:

   • Blakemore 2003 - ideo motor movements in PET study using hypnotised normal subjects.  idea motor movements = unconscious (ougie boards).  subjects had arms attached to a pulley system when in PET scanner.  Active movement of arm, real passive movement, deluded passive movement (told pulley would move arm but it didn't - arms still moved).  Deluded passive movement seen as highly involuntary - claimed they were not responsible for movement.  cerebellum had more diffuse activity for deluded passive movement and significant activation.  partial cortex had more activity in DPM, involvement makes it feel externally generated.  - use of hypnotisable subjects = highly suggestible
2. identical movements are processed different depending on whether they are attributed to the self or to an external source
3. network involving cerebellum and parietal cortex - overactivity may underlie misattributions

1. Spence 1996

   Annotations:

   • Spence 1996 - problem to do with timing of awareness - if aware of consequences before aware of predicted outcome then this is not normal experience of self generated actions and so must be external
2. Jeannerod 1992/2003

   Annotations:

   • Jeannerod - delusions are due to a dysfunction in a representational system dedicated to coding third person information
3. Firth and Blakemore - the motor system does make provision for internalising actions and intentions of others

1. Stimulation theory (1994/2003)

   Annotations:

   • Stimulation theory - observer builds a model of the actions they see which can be used to under the intentions of another.  actions of others represented to same extent as own actions so need to be distinguished.  constant question - them or me?
2. the who system

   Annotations:

   • the who system - different representations for different aspects of monitoring.  conscious judgments about movements are dependent on a 3rd person representation system whereas control of movement is dependent on 1st person info.  delusions of control can be explained by failing to monitor 3rd person signals that enable them to make judgments about their own actions.
3. shared representations and the who system

   Annotations:

   • shared representations and the who system:  specific mechanisms exist that are responsible for the active attribution of action to another agent or the self.  certain components of these self other systems overlap which can cause delusions of agency.  if we see another performing an action we have a representation of it but are aware that it is someone else performing the action.  in schizophrenics the overlap between self/other systems is much larger - they have a problem with shared representations.  they cannot distinguish between own actions and representations of others actions
4. agency and the who system

   Annotations:

   • the who system is responsible for discriminating between self generated action and action of others.  mechanism is depended on shared and overlapping representations - can become dysfunctional in pathology and psychosis
5. Evidence
   1. Ruby 2001

      Annotations:

      • Ruby 2001 - brain imaging study on actions from different perspectives.  1st person perspective - inferior parietal lobe activation. 3rd person perspective = activation in symmetrical area in rh.  distinct and overlapping systems involved in processing action - observers can represent others actions and thus can infer mental states of others by drawing on own representations.  3 systems - what, where, who
   2. doesn't necessarily go against forward model

Annotations:

• mirror neurons - found in monkeys - unethical to look for them in humans.  fire during a self generated movement and when seeing another perform an action. 

1. premotor theory of attention

   Annotations:

   • pre motor theory of attention - actions and motor prep take place when observing actions.  system is involved in understanding actions, with links to theory of mind.  the motor area is always ready to act

1. delusion in body limb ownership

   Annotations:

   • phantom limb syndrome - perception of a limb that no longer exists.  
   1. deafferentation

      Annotations:

      • deafferentation - certain brain areas no longer receive feedback so old representations can no longer be used.  leads to dramatic changes in somatosensory map.   In Phantom limb this process has become dysfunctional and the brain is still relying on old representations
      1. neural remapping

         Annotations:

         • neural remapping - Ramachandren 1997 - synchronous stimulation of an object and unseen body part can make you feel as if sensation is coming from object.  suggestive of a highly fluid sense of self ownership and body representation.  remarkable level of neural plasticity in adult brain
2. rubber arm illusion

   Annotations:

   • rubber arm illusion - visual  info updates body representations when trying to interpret somatosensory stimulation.   Botnivick 1998 - the first Ehhrsson 2007 - threatening a rubber hand produces an anxious response - stabbing movement, compared brain response.  anxiety responses in bilateral insula and bilateral ACC.  relationship between vividness of illusion and anxiety response - implies feeling of ownership so strong it replaces real limb.  (compared to stabbing movements to real hand)
3. very simple manipulations can confuse the brain on things it has held certain for years