14.1 Lateralisation Function

Question 0

The ____ ____ of the cerebral cortex is connected to skin receptors and muscles mainly on the right side of the body. The ____ ____ is connected to skin receptors and muscles mainly on the left side.

Answer 0

left hemisphere : right hemisphere

Question 1

The human brain is ____. The left hemisphere has somewhat different functions from the right hemisphere.

Answer 1

asymmetrical

Question 2

As an exception to this rule, ____ hemispheres control the trunk muscles and facial muscles.

Answer 2

both

Question 3

Left hemisphere ____ only the right half of the world. The right hemisphere ____ only the left half of the world.

Answer 3

sees

Question 4

Each hemisphere gets ____ information from both ears but slightly stronger for the contralateral ear.

Answer 4

auditory

Question 5

Taste and smell, however, are ____. Each hemisphere gets taste information from its own side of the tongue and smell information from the nostril on its own side.

Answer 5

uncrossed

Question 6

The left and right hemispheres of the cerebral cortex exchange information through a set of axons called the ____ ____ and through the anterior commissure, the hippocampal commissure, and a couple of other small commissures.

Answer 6

corpus callosum

Question 7

Information that initially enters one hemisphere crosses quickly so that both hemispheres have access to the ____.

Answer 7

information

Question 8

The two hemispheres are not mirror images of each other. In most humans, the left hemisphere is specialised for ____. The functions of the right hemisphere are more difficult to summarise.

Answer 8

language

Question 9

Such a division of labour between the two hemispheres is known as ____.

Answer 9

lateralisation

Question 10

If you had no corpus callosum, your left hemisphere could react only to information from the ____ side of your body, and your right hemisphere could react only to information from the ____.

Answer 10

right : left

Question 11

Let’s consider how the eyes connect to the brain. The hemispheres connect to the eyes such that each hemisphere gets input from the opposite half of the ____ ____. That is, the left hemisphere sees the right side of the world, and the right hemisphere sees the left side.

Answer 11

visual world

Question 12

Light from the right half of the ____ ____ (what is visible at any moment) strikes the left half of each retina, and light from the left visual field strikes the right half each retina. The left half of each retina connects to the left hemisphere, which therefore sees the right visual field.

Answer 12

visual field

Question 13

The ____ system is organised differently. Each ear sends the information to both sides of the brain, because any brain area that contributes to localising sound must compare input from both ears. However, each hemisphere does pay more attention to the ear on the opposite side.

Answer 13

auditory

Question 14

Damage to the ____ ____ prevents the two hemispheres from exchanging information.

Answer 14

corpus callosum

Question 15

Occasionally, surgeons sever the corpus callosum as a treatment for severe ____, a condition characterised by repeated episodes of excessive synchronised neural activity.

Answer 15

epilepsy

Question 16

People who have undergone surgery to the corpus callosum, referred to as ____ ____, maintain their intellect and motivation, and they still walk without difficulty.

Answer 16

split-brain people

Question 17

However, if split-brain people are asked to pretend they are hitting a golf ball, threading a needle, or attaching a fishhook to a line, they struggle with any task that is not ____ to them.

Answer 17

familiar

Question 18

Split-brain people can use their two hands ____ in a way that other people cannot.

Answer 18

independently

Question 19

The difficulty of simultaneously moving your left hand one way and your right hand a different way reflects a ____ ____ more than a motor limitation. Split-brain people have no troubleprone planning two actions at once.

Answer 19

cognitive difficulty

Question 20

The left hemisphere is dominant for speech production in more than 95% of _____ and nearly 80% of left-handers.

Answer 20

right-handers

Question 21

Not many left-handers have complete right-hemisphere dominance for speech. And more common pattern is ____ left- and right-hemisphere dominance.

Answer 21

mixed

Question 22

In contrast to speech production, speech ____ is more equally divided. The left hemisphere understands speech better than the right hemisphere, but for most people, the right hemisphere understands speech reasonably well, except with complex grammar.

Answer 22

comprehension

Question 23

A split-brain person can name an object after viewing it briefly in the right visual field and therefore the left hemisphere. The same person viewing a display in the left visual field (right hemisphere) usually cannot _______.

Answer 23

name or describe it

Question 24

Many people who have ________ stutter, although not all people who stutter have bilateral control of speech. Perhaps having two speech centres produces competing messages to speech muscles.

Answer 24

bilateral control of speech

Question 25

Each hemisphere of a split-brain person produces information independently of the other. In the first weeks after surgery, the hemispheres act like ____ ____ sharing one body.

Answer 25

seperate people

Question 26

The corpus callosum does not heal, but the brain learns to use the ____ ____ between the left and right hemispheres.

Answer 26

smaller connections

Question 27

The right hemisphere is better than the left at ____ the ____ in people’s gestures and tone of voice, such as sadness or happiness.

Answer 27

perceiving the emotions

Question 28

If the left hemisphere is damaged (and therefore prevented from interfering with the right hemisphere), the right hemisphere is free to make ____ ____.

Answer 28

reliable judgements

Question 29

In contrast, people with damage in parts of the right hemisphere speak in a monotone voice, do not understand other people’s ____ ____, and usually fail to understand humour and sarcasm.

Answer 29

emotional expressions

Question 30

The right hemisphere is dominant for ____ emotions in others, including both pleasant and unpleasant emotions.

Answer 30

recognising

Question 31

The right hemisphere also appears more active than the left at comprehending ____ ____.

Answer 31

spatial relationships

Question 32

The left hemisphere focuses more on ____ and the right hemisphere more on ____ ____.

Answer 32

details : overall patterns

Question 33

The human brain is specialised to attend to language ____.

Answer 33

sounds

Question 34

Norman Gershwin and Walter Levitsky (1968) found that one section of the temporal cortex, called the ____ ____, is larger in the left hemisphere for 65% of people.

Answer 34

planum temporale

Question 35

The corpus callosum gradually grows and thickens as myelin increases around certain axons during ____ and ____.

Answer 35

childhood and adolescence

Question 36

The corpus callosum also matures by ____ many axons. At an early stage, the brain generates far more axons that it will have a maturity.

Answer 36

discarding

Question 37

Rarely, the corpus callosum forms ____ or not at all, possibly for genetic reasons. People born without a corpus callosum are unlike people who have had it cut later in life.

Answer 37

incompletely

Question 38

First, whatever prevented formation of the corpus callosum undoubtably affects brain development in other ways. Second, the absence or near absence of the corpus callosum induces the remaining brain areas to develop ____.

Answer 38

differently

Question 39

People born without a corpus callosum perform more slowly or less accurately than average on tasks that require ____ between the two hemispheres.

Answer 39

corporation

Question 40

However, those born without a corpus callosum performed ____ ____ on many tasks where split-brain people fail. They verbally describe what they feel with either hand and what they see in either visual field. They also feel objects with the two hands and say whether they are the same or different.

Answer 40

reasonably well

Question 41

Each ____ develops pathways connecting it to both sides of the body, enabling the left (speaking) hemisphere to feel both the left and right hands.

Answer 41

hemisphere

Question 42

Also, the brains other commissures become larger than usual, including the ____ ____, which connects the anterior parts of the cerebral cortex, and hippocampal commissure, which connects the left and right hippocampi.

Answer 42

anterior commissure

Question 43

The extra development of these other commissures party ____ for the lack of a corpus callosum.

Answer 43

compensates