Split Brain

Question 1

What is the corpus callosum?

Answer 1

The bundle of nerves that allows the 2 hemispheres to interact and perform contralateral control

Question 2

Where do visual processes cross over at?

Answer 2

The optic chiasm

Question 3

What things happen in the left hemisphere?

Answer 3

Logic
Maths
Science
Language
View objects in the right visual field
Known as the major hemisphere as it processes language
Broca’s and Wernicke’s area is also found in the left

Question 4

What things happen in the right hemisphere?

Answer 4

Creative
Arts
Holistic thoughts
Music
Drawing
Facial recognition
Spatial tasks
Viewing objects in left visual field
Minor hemisphere- can’t process language
Does contribute to emotional context to words though

Question 5

What is interesting about the processing of information?

Answer 5

The right side of the brain processes information from the left half of the body and vice versa

Question 6

What joins the 2 halves of the brain?

Answer 6

The corpus callosum

Question 7

What is a commissurotomy?

Answer 7

The division of the 2 hemispheres by surgery

Question 8

Is the optic nerve severed during a commissurotomy?

Answer 8

No

Question 9

How many participants in the split-brain procedure?

Answer 9

11

Question 10

What type of experiment was it?

Answer 10

Quasi

Question 11

Why did the ppts have their corpus callosum cut out?

Answer 11

To treat epilepsy

Question 12

What does epilepsy cause?

Answer 12

An electrical storm in the brain and produces a seizure for the patient

Question 13

What does severing the hemispheres do?

Answer 13

Reduces the seizures a patient has

Question 14

What did the participants have to do?

Answer 14

Gaze at a fixation point in the centre of the screen
Images/words are flashed to either side of the fixation point for one tenth of a second- this tests what they are seeing in each visual field
The participant is then asked to say what they saw, write what they saw or to feel from a hidden selection of objects to choose the one that matches what they thought they saw

Question 15

FINDINGS: object displayed in the RVF and processed in the LH?

Answer 15

PPTS can describe it in speech and writing

Question 16

FINDINGS: objects displayed in the LVF and processed in the RH?

Answer 16

PPTS cant say what they have seen and instead say they have seen nothing
But if they are asked to use the LEFT hand to feel for a matching object on the table, they can do so while still insisting nothing was seen

Question 17

Patients saw a picture in their RVF and was processed by LH- can they verbally describe the picture?

Answer 17

Yes- can verbally describe and write it down

Question 18

Patient saw a picture in their LVF and processed by RH- can they verbally describe the picture?

Answer 18

No- report to seeing nothing at all

Question 19

Tactile tests: the patient has an object placed in their right hand that they cant see (processed by LH)- can they speak and identify the object by reviewing various objects?

Answer 19

Yes- verbally describe what they feel and can identify the object when reviewing

Question 20

Tactile tests: the patient has an object placed in their left hand that they cant see and it is processed by RH. Can they speak and identify the object by reviewing various objects?

Answer 20

No- processed in right hemisphere
They make wild guesses as to what the object is, however when they are given the chance to identity objects, they felt they can do this

Question 21

Tactile tests: patient has an object placed in either hand (they cannot see). Can their hands find the correct objects?

Answer 21

Each hand searching for its own object
If the opposite hand picks up the object that the left/right hand is looking for, the object is rejected- leading to confusion
The right-hand object can only be successfully found by the right hand and the same for the left hand

Question 22

Drawing tasks: a picture is presented in the RVF processed by the LH- can they draw this?

Answer 22

Can draw the photo but not very well with their right hand

Question 23

Drawing tasks: a picture is presented in the left visual field presented by the right hemisphere- can they draw this?

Answer 23

Can draw a clear photo with their left hand despite being right handed usually

Question 24

Two different objects are displayed to each visual field- they are asked to draw with left hand and verbally say what is drawn- can they do it?

Answer 24

They drew what was on the left side of screen (the case) because RH controls left but they said it was on the right side of the screen where the key was- this is because their LH has language and is trying to reason with what they have said

Question 25

Presented with 2 words simultaneously in each visual field e.g. key and bottle. Must select the key with their left hand and say bottle whilst doing it

Answer 25

Same result as before- they would be able to select a key with their left hand but say the word bottle If asked to draw what they can see, they would draw a key while they said the word bottle

Question 26

When patients were shown composite faces (2 different faces together) then asked to match what faces they saw. Which hemisphere will be able to give a verbal description and which one will choose the matching picture correctly?

Answer 26

If RVF to left hemisphere a verbal description can be given If LVF to right hemisphere can select the matching picture

Question 27

What is the RH responsible for?

Answer 27

Recognising faces

Question 28

What is the LH responsible for?

Answer 28

Language

Question 29

Speech: left part of the brain??

Answer 29

Production of speech Comprehension of the literal meaning of speech

Question 30

Speech: right part of the brain?

Answer 30

Emotional tone- understanding jokes and humour Sarcasm Emotional content of speech

Question 31

Auditory: left?

Answer 31

Sounds related to speech

Question 32

Auditory: right?

Answer 32

Non-language environmental sounds (e.g. rain)

Question 33

Left: visual?

Answer 33

Fine details

Question 34

Right: visual?

Answer 34

Bigger picture Spatial processing (e.g. arranging pieces of a puzzle/drawing a picture)

Question 35

AO3: LIMITATIONS?

Answer 35

Small sample size Hard to replicate Some had their corpus colosseum out for a longer time- few weeks vs 5 years- brain may have developed due to plasticity Can’t ethically repeat Low ecological validity- done in a lab- may have developed demand characteristics Low temporal validity- done in 1968

Question 36

AO3: STRENGTHS?

Answer 36

High ethics- they had already had the surgery Lab based- very scientific High mundane realism- used everyday items (banana,apple,keys) which increases internal validity Practical application- only suggest if epilepsy is awful