1
Q
What does dual consciousness mean ?
A
- two separate, independent centers of consciousness, one in each cerebral hemisphere
2
Q
what does commissurotomy mean ?
A
- Regular way = only cutting the corpus collosum
- full way = cutting the anterior commissure and the corpus collosum
3
Q
What is the impact of an commissurotomy on a person ?
A
- It has no harmful effect in daily life
4
Q
How does vision in general work ?
A
- left hemisphere sees right visual field (RVF) & vice vers
5
Q
What are some pros of commissurotomy ?
A
- Allows to study hemisphere functioning directly, by seeing what the intact hemisphere can do
6
Q
What are some cons of commissurotomy ?
A
- 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
7
Q
How do u test unilateraly ?
A
- Tactile testing
- visual testing via Projection tachistoscope (t scope)
- Unilateral testin = clearly staying in one visual field or in the other
8
Q
Explain how tactile testing works ?
A
- 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)
9
Q
Explain how visual testing via the projection tachistoscope (t scope) works ?
A
- 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
10
Q
What is so special about the right hemisphere based on the unilateral testing ?
A
- 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
11
Q
What was so one special experiment regarding visual unilateral testing ?
A
- The naked woman experiment
12
Q
What happens in the naked woman experiment ?
A
- 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
13
Q
What is meant by the hallmarks of split brain syndrome ?
A
- Differences between split-brain patients and healthy adults
- They explain if conscious unity necessarily breaks down when the corpuscallosum is removed
14
Q
Was the explanation of the hallmarks of the split brain theory good ?
A
- 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
15
Q
Name the 5 hallmarks of split brain theory:
A
- Response x visual field interaction
- Hemispheric sepcialistaion
- post hoc confabulation
- split attention
- inability to compare stimuli across midline
16
Q
Explain Response x visual field interaction more in depth:
A
- 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)
17
Q
Explain Hemispheric sepcialistaion more in depth:
A
- 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
18
Q
Explain post hoc confabulation more in depth:
A
- 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
19
Q
Explain split attention more in depth:
A
- 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
20
Q
Explain inability to compare stimuli across midline more in depth:
A
- 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
21
Q
What did the 5 hallmarks principle leaded to ?
A
- to the classical model of split brain patients
- In general that means: consciousness is split in split-brain patients
22
Q
What types of classical models do we have ?
A
- partial consciousness model
- Split consciousness model
23
Q
Explain the partial consciousness model ?
A
- 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)
24
Q
Explain the split consciousness model ?
A
- 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
25
Name the key concept which differentiates both model:
- Either the right hemisphere gives rise to automatic action (partial) or rise to conscious actions
26
Which test explaines the strength of the RH and how does it work ?
- Block-design test: use set of coloured blocks (each side has a different colour) to construct a pattern that matches the sample pattern in a picture
- Easy with LH (RHemi)
- Since RH is good at construction
27
Explain the chimeric figure test and name it results:
- A face picture was flashed and then a head split in two different face halfes
- which face half matched the previous face
- subject had to choose which face it saw either trough pointing (R hemis) or trough verbal response (L hemis)
- Pointing = Left half
- verbal = right half
- RH = is better
28
What is meant by visaul completion ?
- subjectively see figure as complete although they’ve only seen half
29
What is meant by other minds problem ?
- the speaking LH has no direct knowledge of the RH -> can only make inferences based on emotional reaction or behaviour initiated -> to LH, RH is the “other mind”
30
What is meant by intelligent behaviour the criterion for consciousness by sperry
- shows adaptivity to current sitch and is controlled by flexible thought processes
- Both hemisphere contain IB
31
What are some evidence for the spilt/dual consciouss theory ?
- Has high intelligent action (Cognitive task with the horse)
- The alien syndrome (one hand seems out of control)
- Cross cueing
- RH is capable of self awareness
- RH is capable of knowing social values
32
Explain the cognitive horse task:
- Horse picture flashed on LVF
- Could not draw the horse but what goes along with it (saddle) even though he could also not recognize it
- Started to recognize it was a saddle when the actual horse was seen in RVF
33
What does alien hand mean ?
- conflict between the left and right hemispheres (2 consciousness)
34
What is meant by cross cueing ?
- the left hemisphere is able to guess what the right hemisphere has seen or felt by noticing the right hemisphere’s overt responses to the situation (nude woman example
- Rh attempts to send signal to the LH
- only works for immediate short term goals
35
What is meant by Inadvertent cross cueing ?
- spontaneous but unintentional responses (interpreted by LH)
- versehentlcih
36
How was self awareness tested in the RH ?
- Via self recognition since SR is the minimum criterion for self awareness
- Self awareness is based on brainstem mechanism (overcome corpus collosum)
- Pictures were shown to the patient via a Z lens and whenever the patient saw himself an emotional outburst was shown
37
How were social values tested in the RH ?
- pictures were shown again trough out the Z lens and the patient had to indicate via thumb up or thumb down if he likes the picture or not
- even though they could not verbally report what they have seen they liked pictures according to social values and also disliked pictures accoridng to social values
38
What was gazzingas opinion on sperry ?
- only the left hemisphere gives rise to consciousness, while the right hemisphere processes info only in an unconscious manner
- but there are some exceptions
- Partial consciousness model
- Left H contains Interpreter system = consciounsess
39
Why are there some exceptions according to gazzinga ?
- Because if the right H contains langauge ability then they could be conscious
40
What is the function of a Z Lens ?
- peeps could examine photo while LH couldn’t see
41
Why is the left hemisphere so the dominant hemipshere ?
- beacuse it constains the language ability
42
What was so special about patient PS ?
- he prooved that language comprehension was possible in the right hemisphere.
- Example: When patient saw a his girlfriend he could spell out her name based on scrabbel letters
- understood the action verbs task -> If is stated run he start to run
43
What was a limitation of the patient PS ?
- BUT anterior commissure wasn’t cut so direct emotional communication was possible
44
Explain the idea of the interpreter system by gazzaniga:
- Mind is made up of independent modules
- Each module = is a functional unit
- The module can not produce verbal responses but can produce overt responses (emotional reaction)
- modules are unconsciouss
- The interpreter sytsem interpreted diversse action of modules
- languagse sytsem refined the output of the interpreter system
45
What are some functional units of modules ?
- receive information or retrieve memories or trigger emotional reaction or produce behaviour
46
Name some proof of the interpreter system: Experiment one
- Experiment one: Patient had 2 pictures simultaneously showing. One picture for the right H and one for the left H. The pateint was able to link both objects to an object which goes along with it. Then the left hemisphere tried verbally to explain the responses. Verball respond was based only on the RVF (picture of a claw) and the LVF was just integreated in the story
47
Name some proof of the interpreter system: Experiment two
Two sepperate stories were given to each hemisphere:
- Normal people combines infomration (read from right to left but spilt brain patient can only read one VF and then the other
- Left hemisphere could report the story immediately
- right hemisphere only in fragments
- After a while the LH integratted both stories into one
48
What is one of gazzingas conclusion ?
- Mental unity is a illusion
- actions are controlled by unconsciouss modules and conscious modules
- the interpreter system just pretents that there is a consciouss unity
49
Name all theories of gazzinga:
1. Wherever there is a languae ability there will be cnsciousness
2. consciousness is the “output of the left-brain interpreter system.”-> the RH activity is only there beacuse of nonconscious modules (emotional reaction)
50
What are some critics on gazzaniga ?
- Gazzaniga only used brains which were damaged prior to surgery
51
What is the major conclusion of gazzaniga ?
- Primary consciousness (non concscious modules) could be found in both hemispheres, but reflective consciousness is limited to LH
52
What is meant by the consciouss unity spilt eprception model ?
- opposing to gazzaniga it states that consciousness is unified because patients behave and feel normal
- Differences are explained via unitergrated perception
53
what is meant by unitergrated perception ?
- Both hemisphere kinda work like being ‘out-of-sync’ movie
- one perception get there before the other
- both visual information and cognition might indeed be split but get integreated by a single central agent
54
What is the difference between the calssical theory of consciousness and the consciouss unity split perception model ?
- C model has one central agents for each perception (so allways seperated)
- IN TOTAL 2 central agents
55
What are some different theories of consciousness ?
- Integrate Information Theory (IIT)
- Global Workspace Theory (GW)
- Recurrent Processing (RP)
56
What is meant by the integrate Information theory ?
- When integration within a subsystem is larger than connection btw subsystems, consciousness will arise as a function of the subsystem rather than the system as a whole
- Supports splits brain since intrhemispheric is more connected then interhemispheric
57
What is meant by the Global Workspace Theory (GW) ?
- Cerebral hemispheres house a global workspace (like headquarters) an only the information processed by this GW reaches consciousness
- could be both partial or split since either each H creates a GW or it stays at one GW
58
What is meant by the Recurrent Processing (RP) theory ?
- phenomenal consciousness can arise through local RP btw modules, even in the absence of global/ integrative processes ->
- But reportable consciousness, still needs strong integration btw hemispheres
59
Which theories can explain consciouss unity ?
- subcortical tehory
| - Functional notion
60
Explain the subcortical theory:
- Unified consciousness remains intact when a minimal number of axonal connections btw subcortical structures exists
61
Explain the functional notion theory:
- 1. conscious unity is strongly related to functional unit
2. Functional unity means that different parts of a system operate mostly in conjunction(connection), ratherthan independently
3. Connection is based on common source not trough direct linking
- Syncronized neuronal activity is the proof -> was shown in resting state in split brain patients
Consciousness
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