Neuropsychological disorders of self-awareness 6B

Only the LH has consciousness (Past) Both has consciousness (Now)

(Gazzaniga)

There is no whole number of minds that these patients can be said to have

(Nagel)

Each hemisphere has a mind of its own even in the normal case

(Puccetti)

Both hemispheres have a stream of consciousness independent of the other, separated by the surgery

(Sperry)

Right hemisphere consciousness:

* only phenomenal consciousness? * only rudimentary reflective abilities?

Capgras delusion

- A delusion where a person thinks a family or friend has been replaced by an identical looking imposter (this is not my wife, this is not my house) - Disruption of "affective familiarity" when looking at the faces of close persons - Cognitive face recognition still works! > Disconnection between cognitive face-processing and emotional face- processing?

Delusion:

- An obviously false belief that is held with strong conviction in the face of no supporting evidence or explicit contrary evidence. - A belief that for outsiders seems obviously false, but still is held by the person with high conviction even in the face of contrary evidence, and cannot be corrected by reasoning or evidence

What does Right-Hemisphere "Devil's Advocate" do

- Critically monitors beliefs and LH "stories" against the facts - Questions, challenges, and finally overthrows old beliefs if they do not correspond to reality - Initiates "revolutions" and "paradigm shifts" in belief systems - Hyperactivation of RH: "depressive realism"; negative, self-critical rumination.

What does Left-Hemisphere Interpreter do

- It creates our "narrative self" ; the "story of our life" (around our corebeliefs) - Produces post-hoc explanations, causal interpretations, and confabulations (especially about one's own choices and behaviours) - Maintains the "Status Quo" and defends core beliefs and positive interpretations (especially about the "narrative self") - Uses "confirmation biases" & Freudian defense mechanisms

What cause the Capgras delusion?

Caused by brain damage affecting the emotional components of face recognition.

Fregoli delusion

- Strangers are familiar people in disguise! - "someone (emotionally significant) keeps following me under disguise" - An over-active emotionally important "person identity node" that overthrows cognitive face recognition

Current interpretations

- The right hemisphere seems to deal mainly with raw experience in an unembellished way. The left hemisphere, is constantly, almost reflexively, labeling experiences, making inferences as to cause, and carrying out a host of other cognitive activities... - The left hemisphere is busy differentiating the world whereas the right is simply monitoring the world.

status quo

Existing state or condition

Gazzaniga (split-brain studies):

The Left-Hemisphere "Interpreter"

Ramachandran (anosognosia etc.):

The Right-Hemisphere "Devil's Advocate" to question the status quo and look for global inconsistencies.

Cotard Delusion

The strong belief that: I am dead, my body (or internal organs) have died, I do not exist any more! - Sometimes also the beliefs that: the world is dead, soulless, or doomed - Extreme form of severe psychotic depression and/or RH brain damage

Delusional misidentification syndromes

a rare group of disorders characterized by delusions regarding the identity of familiar individuals

split brain

- When the connections between the hemispheres are cut, epileptic seizures starting from one hemisphere can no longer spread to the other hemisphere - Neither can any information be sent directly from one hemisphere to the other: The hemispheres are functionally isolated from each other. - After recovery from the operation, the patients act, speak, and feel no different than before - In some patients, sometimes the left and the right hand would act in conflict with each other - Subjectively, the sense of having one single, unified conscious self persists - Objectively, the brain is split and (some) stimuli perceived and behaviours elicited independently by the separated hemispheres:

depersonalization

An alteration in experience that people find hard to describe, where the subject feels a strangeness pervading the world and her/his own body, emotions and thoughts.

Split-brain operations may be performed as a last resort to control

Brain surgery that is occasionally performed to treat a form of epilepsy; the surgeon cuts the corpus callosum, which connects the two hemispheres of the brain >> the two brain hemispheres lose all direct contact with each other! - Roger Sperry, Joseph Bogen, Michael Gazzaniga

Experiments using lateralized visual stimuli

Objects presented in the left visual field are perceived by the right hemisphere, and vice versa. Normally, information received by the left hemisphere crosses into the right hemisphere via the corpus callosum, allowing "cross-talk" between the two halves of the brain. When this fiber tract is severed, however, as in split-brain patients, visual information from one hemisphere cannot pass to the other hemisphere. - The right hemisphere can report what it saw by drawing pictures with the left hand - The left hemisphere reports what it saw by writing the word - No subject has seen by the two hemisphere - The Left-Hemisphere Interpreter cooks up a story why supposedly chose to point to the stimulus. >> never explains the behavior by referring to the split-brain: e.g. "It was probably something you told my right hemisphere to do" - Thus, the left hemisphere, the speaking subject, had no idea of the picture seen by the right hemisphere, which was the actual cause of choosing the stimulus

Left hemisphere consciousness:

Phenomenal consciousness + reflective consciousness + self-awareness

Delusional belief system

To explain one's own strange subjective feelings: "The world has changed" (in some bizarre manner)