2. Hemispheres

Question 1

Corpus callosum

Answer 1

A large collection of axons which serve as a bridge for the two hemispheres to communicate

Question 2

Contralateral organisation

Answer 2

Controlling the opposite side

Question 3

Left visual field

Answer 3

The right halves of each eye

Question 4

Right visual field

Answer 4

The left halves of each eye

Question 5

Left hemisphere

Answer 5

Language
Production of speech
Reading, writing
Verbal memory

Question 6

Right hemisphere

Answer 6

Emotional perception
Spacial awareness
Faces
Understands speech, cannot produce it

Question 7

Cerebral lateralization

Answer 7

Hemispheres/different areas of the brain developing different, specialised skills

Question 8

Cause of lefthandedness

Answer 8

Either the right or left hemisphere will be dominant, resulting in left or right handedness

Unclear why left-handedness is rare as it does not cause any severe disadvantages

Question 9

Possible causes of lefthandedness

Answer 9

• Fetus predisposition
  
  • Which hand you lay on more
• Genetics
• Slower development of RH
• Prenatal stress (infections, increased testosterone)
• Vitamin D levels
• Testosterone levels

Question 10

Right-sided world hypothesis

Answer 10

World is designed for right-handed people so left-handed people have more accidents

Question 11

Survival of the unexpected

Answer 11

Gives left-handed people certain advantages like in sports and music

Question 12

Lateralization

Answer 12

Division of responsibilities between the hemispheres

Question 13

Split brain patients

Answer 13

Severing of the corpus callosum to treat severe epilepsy

Question 14

Effects of split brain on epilepsy

Answer 14

• Prevents the seizure crossing over to the other side of the brain
  Seizures occur on only one side of the body
• Less frequent
• Shorter
  
  • Normally epileptic activity bounces between the hemispheres

Question 15

Behaviour changes in split brain patients

Answer 15

• They can use their hands independently in ways that we can’t
  
  • Drawing two different shapes simultaneously or the same shape at different speeds

Behavioural effects when stimuli is presented to only one side of the body
- Information cannot cross to the other hemisphere
- Can only point to what each hemisphere saw
- Cannot verbally describe what the right hemisphere saw but is able to point it out

• Initially, patients experience conflicts between the two sides of their body as they don’t communicate and do separate, opposing things
  
  • e.g. right hand picks up groceries, left hand puts them back
  • This usually passes with time

Question 16

Unchanged behaviour in split brain patients

Answer 16

• There is no effect on familiar tasks like tying shoes
• Intellect, motivation, speech are all the same

Question 17

Interpreter

Answer 17

the tendency of the left hemisphere to explain and defend its actions when the cause is unclear

Question 18

Split brain & Children

Answer 18

• Behaviours of split-brain patients are comparable to those in young children as the corpus callosum develops from 3-5 years old
• Sometimes, children are born without the corpus callosum - both hemispheres will be active during speech
  
  • Ordinarily, both hemispheres are in charge of language but the left will eventually block the right, this doesn’t happen without a corpus callosum

Question 19

Planum temporale

Answer 19

• Comprehension of language
• Damage - aphasia (trouble with language)
• Bigger in the left hemisphere

Question 20

Heschl’s Gyrus

Answer 20

• Located in the later fissure
• Primary auditory cortex
• Asymmetrical - right one is bigger than the left - might have an impact on split brained patients
• Bigger in the left hemisphere

Question 21

3 Theories about Cerebral Lateralization

Answer 21

Analytic (LH) and Synthetic (RH) Theory
Motor Theory
Linguistic Theory

Question 22

Analytic (LH) and Synthetic (RH) Theory

Answer 22

2 basic modes of thinking, one for each hemisphere
Analytic (LH) - logical, computer-like thinking
Synthetic (RH) - organizes & processes information as a whole, not the sum of its parts

Question 23

Frontal operculum AKA Broca’s Area

Answer 23

Speech production; more pronounced in LH

Question 24

Motor Theory

Answer 24

LH is specialised to the control of fine movements, with speech falling under this category

Question 25

Linguistic Theory

Answer 25

The primary role of the LH is language
Opposes prior two theories which see language as a secondary role of the LH
Evidence: damage leads to disruption of sign language, but not pantomime gestures

Question 26

Sodium Amytal Test

Answer 26

Sodium amytal is injected into the carotid artery on one side of the neck to numb certain parts of the corresponding hemisphere for a short time

Purpose: to study lateralization

Question 27

Dichotic Listening Test

Answer 27

Headphones play different numbers in each ear, see which one the participant heard to show which hemisphere was more dominant

Question 28

What type of matter are axons?

Answer 28

White matter

Question 29

What type of matter are neuron bodies

Answer 29

Grey matter

Question 30

Functional brain imaging

Answer 30

fMRI, PET - brain activity; LH - language

Question 31

Visual completion

Answer 31

being unaware of a scotoma (blind spots) -> brain filling them in by using information from the surrounding areas of the visual field

Question 32

Helping-hand phenomenon

Answer 32

one hand grabbing the other hand and redirecting it toward the stimuli thought to be right by that certain hemisphere

Question 33

Cross-cueing

Answer 33

hemispheres communicating with each other by an external route