Task 6 Flashcards
What does dual consciousness mean ?
- two separate, independent centers of consciousness, one in each cerebral hemisphere
what does commissurotomy mean ?
- Regular way = only cutting the corpus collosum
- full way = cutting the anterior commissure and the corpus collosum
What is the impact of an commissurotomy on a person ?
- It has no harmful effect in daily life
How does vision in general work ?
- left hemisphere sees right visual field (RVF) & vice vers
What are some pros of commissurotomy ?
- Allows to study hemisphere functioning directly, by seeing what the intact hemisphere can do
What are some cons of commissurotomy ?
- The commissurotomy is only done by patient with prior damage -> not generalizabel
- Only have a small sample
- lots of variability among patients
- Functional reorganisation prior to surgery might have occurred
- plasticity after organization
How do u test unilateraly ?
- Tactile testing
- visual testing via Projection tachistoscope (t scope)
- Unilateral testin = clearly staying in one visual field or in the other
Explain how tactile testing works ?
- Ask to identify objects by touch alone (inside box)
- Right hand could name the objcet
- left hand could not name the object but (it could show what the object was used for)
Explain how visual testing via the projection tachistoscope (t scope) works ?
- focus on central cross, picture shown on either left or right side and u had to na,e the the objects
- RVF = naming, LVF = no naming but could select matching object with left hand and also was able to select objects that go with the shown object
What is so special about the right hemisphere based on the unilateral testing ?
- Right hemisphere can not tell the object it has no language center but
1. it knows what kind of object it is and
2. it understand it concepts (what it is used for)
3. initiated automatic emotional reaction
What was so one special experiment regarding visual unilateral testing ?
- The naked woman experiment
What happens in the naked woman experiment ?
- When nude shown to LVF, couldn’t name but showed embarrassment
- Right hemisphere initiated automatic emotional reaction
- Left hemisphere tried to make sense of right hemisphere’s actions -> which eventually leads to the correct answer
What is meant by the hallmarks of split brain syndrome ?
- Differences between split-brain patients and healthy adults
- They explain if conscious unity necessarily breaks down when the corpuscallosum is removed
Was the explanation of the hallmarks of the split brain theory good ?
- no they failed
- Why because Response x visual field interaction is not present in all split brain patientes
- And other four hallmarks were present in healthy people as well
- They are not the evidence for a disturbed conscious unity
Name the 5 hallmarks of split brain theory:
- Response x visual field interaction
- Hemispheric sepcialistaion
- post hoc confabulation
- split attention
- inability to compare stimuli across midline
Explain Response x visual field interaction more in depth:
- it means = When a stimulus is presented to the left visual field, the patient can only respond adequately with his/her left hand (it can not report because the data goes into the the muted brain)
Explain Hemispheric sepcialistaion more in depth:
- Each H is better at a certain task
- LH: language production,superior in verbal and conceptual tasks, self-recognition
- RH: non-verbal tasks, particularly visuospatial tasks involving drawing and construction, face recognition
Explain post hoc confabulation more in depth:
- u give a wrong explanation for u behaviour
- LVF sees a bell and u have to point to the object which u can but ur reasoning is wrong ( u come up with a wrong story)
- Just like mirror neurons in healthy people
Explain split attention more in depth:
- Each hemisphere has different points of attention (two different attentions)
- Object-based & space-based attention are situated in different hemispheres
- Simmilar in heathy adults since each H tracks info independently and only shares when neccesary
Explain inability to compare stimuli across midline more in depth:
- If stimulus is presented in one VF and the other stimulus is presented in the other VF then the pateint can not tell the different
- Exception: Split brain patient was ablte to tell if apparent motion was present and if two lines runin parallel or coincidend
What did the 5 hallmarks principle leaded to ?
- to the classical model of split brain patients
- In general that means: consciousness is split in split-brain patients
What types of classical models do we have ?
- partial consciousness model
- Split consciousness model
Explain the partial consciousness model ?
- only the left hemisphere gives rise to consciousness, while the right hemisphere onlyprocesses information in an unconscious manner
- key criterion for consciousness is introspective verbal report (IVR)
Explain the split consciousness model ?
- Each hemisphere has its own consciousness independent of each other
- supported by sperry
- IVR is not the key creiterion of consciousness
- the key criterion is intelligent behaviour