Cerebral Lateralization

The highest brain center in humans, the cerebrum, consists of two halves (or hemispheres) connected by a band of fibers called the corpus callosum. Although identical in appearance, the left and the right cerebral hemispheres serve different functions and control different areas of the body. The left cerebral hemisphere controls the right side of the body, and it contains centers for speech, hearing, verb al memory, decision making, and processing of language, to name a few. By contrast, the right cerebral hemisphere controls the left side of the body and contains centers for tactile (touch) sensations, music, and emotional expressions. Thus, the brain is a lateralized organ.

Cerebral lateralization also involves a preference for using one hand or one side of the body more than the other. About 90 percent of adults rely on their right hand (or left hemisphere) to write, eat, and perform other motor functions (involving movement), whereas these activities are controlled by the right hemisphere among those who are left-handed. However, the fact that the brain is a lateralized organ does not mean that each hemisphere is totally independent of the other, for the corpus callosum, which connects the hemispheres, plays an important role in integrating their respective functions.

When do the two cerebral hemispheres being to “divide the work” and become lateralized? It was once thought that lateralization took place gradually throughout childhood and was not complete until adolescence. Now, however, it is believed that brain lateralization may originate in the prenatal period (before birth) and is clearly evidence at birth. For example, it has been noted that about two-thirds of all fetuses end up positioned in the womb with their right ear facing outward, and it is believed that this gives them a right-ear advantage and illustrates the left hemisphere’s specialization in language processing. From the first day of life, speech sounds stimulate more electrical activity in the left side of the cerebral cortex than in the right.In addition, most newborns turn to the right rather than to the left when they lie on their back, and these same babies later tend to reach for objects with their right hand.So it seems that the two cerebral hemispheres may be biologically programmed to assume different functions and have already begun to “divide the labor” by the time a baby is born.

However, the brain is not completely specialized at birth, until puberty (the stage of adolescence), children come to rely more and more on one particular hemisphere or the other to serve particular functions.For example, even though left- or right-handedness is apparent early and is reasonably well established by age two, lateral preferences become stronger over time. In one experiment, preschoolers and adolescents were asked to pick up a crayon, kick a ball, look into a bottle, and place their ear to a box to hear a sound. Only 32 percent of the preschoolers, but more than half of the adolescents, showed a consistent lateral preference by relying exclusively on one side of the body to perform all four tasks. Because the immature brain is not completely specialized, young children often show a remarkable ability to bounce back from traumatic brain injuries as neural circuits that might otherwise have been lost assume the functions of the injured ones. Although adults who suffer brain damage often regain a substantial portion of the functions they have lost, their recoveries are rarely as rapid or as complete as those of younger children. So the remarkable recuperative power of the human brain is greatest early in life, before cerebral lateralization is complete.

What are the implications for children who fail to rely on one hemisphere or the other to perform specific functions? Leslie Tan found that four year olds who have not yet established a dominant hand are more likely than their left- or right-handed age-mates to be uncoordinated and delayed in their motor development. Other research has linked dyslexia – a serious impairment in one’s ability to read that may affect as many as 5 percent of schoolchildren in the United States – to an abnormal pattern of cerebral lateralization for visual/spatial functions. Although not everyone agrees that all forms of dyslexia have a neurological basis, many people with dyslexia do show irregularities in cerebral lateralization that may well contribute to their reading difficulties.

 

1

The highest brain center in humans, the cerebrum, consists of two halves (or hemispheres) connected by a band of fibers called the corpus callosum. Although identical in appearance, the left and the right cerebral hemispheres serve different functions and control different areas of the body. The left cerebral hemisphere controls the right side of the body, and it contains centers for speech, hearing, verb al memory, decision making, and processing of language, to name a few. By contrast, the right cerebral hemisphere controls the left side of the body and contains centers for tactile (touch) sensations, music, and emotional expressions. Thus, the brain is a lateralized organ. Cerebral lateralization also involves a preference for using one hand or one side of the body more than the other. About 90 percent of adults rely on their right hand (or left hemisphere) to write, eat, and perform other motor functions (involving movement), whereas these activities are controlled by the right hemisphere among those who are left-handed. However, the fact that the brain is a lateralized organ does not mean that each hemisphere is totally independent of the other, for the corpus callosum, which connects the hemispheres, plays an important role in integrating their respective functions.

The word “integrating” in the passage is closest in meaning to

Aadjusting

Bdetermining

Ccoordinating

Dperforming

 

2

The highest brain center in humans, the cerebrum, consists of two halves (or hemispheres) connected by a band of fibers called the corpus callosum. Although identical in appearance, the left and the right cerebral hemispheres serve different functions and control different areas of the body. The left cerebral hemisphere controls the right side of the body, and it contains centers for speech, hearing, verb al memory, decision making, and processing of language, to name a few. By contrast, the right cerebral hemisphere controls the left side of the body and contains centers for tactile (touch) sensations, music, and emotional expressions. Thus, the brain is a lateralized organ. Cerebral lateralization also involves a preference for using one hand or one side of the body more than the other. About 90 percent of adults rely on their right hand (or left hemisphere) to write, eat, and perform other motor functions (involving movement), whereas these activities are controlled by the right hemisphere among those who are left-handed. However, the fact that the brain is a lateralized organ does not mean that each hemisphere is totally independent of the other, for the corpus callosum, which connects the hemispheres, plays an important role in integrating their respective functions.

According to paragraph 1, why is the cerebrum considered a lateralized organ?

AIts halves are connected by a band of fibers called the corpus callosum.

BEach hemisphere of the brain is totally independent of the other.

CDifferent sides of the brain are responsible for different functions.

DIt creates a preference for using one side of the body more than the other.

 

3

The highest brain center in humans, the cerebrum, consists of two halves (or hemispheres) connected by a band of fibers called the corpus callosum. Although identical in appearance, the left and the right cerebral hemispheres serve different functions and control different areas of the body. The left cerebral hemisphere controls the right side of the body, and it contains centers for speech, hearing, verb al memory, decision making, and processing of language, to name a few. By contrast, the right cerebral hemisphere controls the left side of the body and contains centers for tactile (touch) sensations, music, and emotional expressions. Thus, the brain is a lateralized organ. Cerebral lateralization also involves a preference for using one hand or one side of the body more than the other. About 90 percent of adults rely on their right hand (or left hemisphere) to write, eat, and perform other motor functions (involving movement), whereas these activities are controlled by the right hemisphere among those who are left-handed. However, the fact that the brain is a lateralized organ does not mean that each hemisphere is totally independent of the other, for the corpus callosum, which connects the hemispheres, plays an important role in integrating their respective functions.

According to paragraph 1, which of the following is true of the corpus callosum?

AIt controls both sides of the body.

BIt connects the two hemispheres of the cerebrum.

CIt determines which side of the body is preferred.

DIt allows each hemisphere to operate independently of the other.

 

4

When do the two cerebral hemispheres being to “divide the work” and become lateralized? It was once thought that lateralization took place gradually throughout childhood and was not complete until adolescence. Now, however, it is believed that brain lateralization may originate in the prenatal period (before birth) and is clearly evidence at birth. For example, it has been noted that about two-thirds of all fetuses end up positioned in the womb with their right ear facing outward, and it is believed that this gives them a right-ear advantage and illustrates the left hemisphere’s specialization in language processing. From the first day of life, speech sounds stimulate more electrical activity in the left side of the cerebral cortex than in the right.In addition, most newborns turn to the right rather than to the left when they lie on their back, and these same babies later tend to reach for objects with their right hand.So it seems that the two cerebral hemispheres may be biologically programmed to assume different functions and have already begun to “divide the labor” by the time a baby is born.

The word “assume” in the passage is closest in meaning to

Aprefer

Btake on

Crecognize

Dseparate

 

5

When do the two cerebral hemispheres being to “divide the work” and become lateralized? It was once thought that lateralization took place gradually throughout childhood and was not complete until adolescence. Now, however, it is believed that brain lateralization may originate in the prenatal period (before birth) and is clearly evidence at birth. For example, it has been noted that about two-thirds of all fetuses end up positioned in the womb with their right ear facing outward, and it is believed that this gives them a right-ear advantage and illustrates the left hemisphere’s specialization in language processing. From the first day of life, speech sounds stimulate more electrical activity in the left side of the cerebral cortex than in the right.In addition, most newborns turn to the right rather than to the left when they lie on their back, and these same babies later tend to reach for objects with their right hand.So it seems that the two cerebral hemispheres may be biologically programmed to assume different functions and have already begun to “divide the labor” by the time a baby is born.

According to paragraph 2, research shows that about two-thirds of all fetuses

Ahave a left hemisphere advantage because of their position in the womb

Bdepend on the right hemisphere to process language

Cchange the left hemisphere to the right and the right to the left

Dhave a brain that does not become fully lateralized until adolescence

 

6

When do the two cerebral hemispheres being to “divide the work” and become lateralized? It was once thought that lateralization took place gradually throughout childhood and was not complete until adolescence. Now, however, it is believed that brain lateralization may originate in the prenatal period (before birth) and is clearly evidence at birth. For example, it has been noted that about two-thirds of all fetuses end up positioned in the womb with their right ear facing outward, and it is believed that this gives them a right-ear advantage and illustrates the left hemisphere’s specialization in language processing. From the first day of life, speech sounds stimulate more electrical activity in the left side of the cerebral cortex than in the right.In addition, most newborns turn to the right rather than to the left when they lie on their back, and these same babies later tend to reach for objects with their right hand.So it seems that the two cerebral hemispheres may be biologically programmed to assume different functions and have already begun to “divide the labor” by the time a baby is born.

The author includes the information that “most newborns turn to the right rather than to the left when they lie on their back” in order to

Asupport the claim that brain lateralization is already evidence at birth

Bshow that position in the womb affects babies’ preferred position after birth

Cexplain why there is more electrical activity in the left side of the cerebral cortex than in the right side

Dprovide an example of a behavior that may encourage brain lateralization

 

7

However, the brain is not completely specialized at birth, until puberty (the stage of adolescence), children come to rely more and more on one particular hemisphere or the other to serve particular functions.For example, even though left- or right-handedness is apparent early and is reasonably well established by age two, lateral preferences become stronger over time. In one experiment, preschoolers and adolescents were asked to pick up a crayon, kick a ball, look into a bottle, and place their ear to a box to hear a sound. Only 32 percent of the preschoolers, but more than half of the adolescents, showed a consistent lateral preference by relying exclusively on one side of the body to perform all four tasks. Because the immature brain is not completely specialized, young children often show a remarkable ability to bounce back from traumatic brain injuries as neural circuits that might otherwise have been lost assume the functions of the injured ones. Although adults who suffer brain damage often regain a substantial portion of the functions they have lost, their recoveries are rarely as rapid or as complete as those of younger children. So the remarkable recuperative power of the human brain is greatest early in life, before cerebral lateralization is complete.

The author cites a study in which “preschoolers and adolescents were asked to pick up a crayon, kick a ball, look into a bottle, and place their ear to a box to hear a sound” in order to

Areject the claim that left- or right-handedness is apparent early in life

Bargue that both children and adolescents use different sides of the body to perform different types of tasks

Cprovide evidence that, as they age, children develop a stronger reliance on one hemisphere over the other

Dprovide examples of tasks that become easier as the brain becomes more specialized

 

8

However, the brain is not completely specialized at birth, until puberty (the stage of adolescence), children come to rely more and more on one particular hemisphere or the other to serve particular functions.For example, even though left- or right-handedness is apparent early and is reasonably well established by age two, lateral preferences become stronger over time. In one experiment, preschoolers and adolescents were asked to pick up a crayon, kick a ball, look into a bottle, and place their ear to a box to hear a sound. Only 32 percent of the preschoolers, but more than half of the adolescents, showed a consistent lateral preference by relying exclusively on one side of the body to perform all four tasks. Because the immature brain is not completely specialized, young children often show a remarkable ability to bounce back from traumatic brain injuries as neural circuits that might otherwise have been lost assume the functions of the injured ones. Although adults who suffer brain damage often regain a substantial portion of the functions they have lost, their recoveries are rarely as rapid or as complete as those of younger children. So the remarkable recuperative power of the human brain is greatest early in life, before cerebral lateralization is complete.

The fact that most adolescents showed a “consistent” lateral preference means that

Athe lateral preferences of most adolescents were stronger than those of preschoolers

Bthe lateral preferences of most adolescents were different from those of preschoolers

Cthe lateral preferences of most adolescents were for the left side of the body

Dthe lateral preferences of most adolescents were the same each time they performed a task

 

9

However, the brain is not completely specialized at birth, until puberty (the stage of adolescence), children come to rely more and more on one particular hemisphere or the other to serve particular functions.For example, even though left- or right-handedness is apparent early and is reasonably well established by age two, lateral preferences become stronger over time. In one experiment, preschoolers and adolescents were asked to pick up a crayon, kick a ball, look into a bottle, and place their ear to a box to hear a sound. Only 32 percent of the preschoolers, but more than half of the adolescents, showed a consistent lateral preference by relying exclusively on one side of the body to perform all four tasks. Because the immature brain is not completely specialized, young children often show a remarkable ability to bounce back from traumatic brain injuries as neural circuits that might otherwise have been lost assume the functions of the injured ones. Although adults who suffer brain damage often regain a substantial portion of the functions they have lost, their recoveries are rarely as rapid or as complete as those of younger children. So the remarkable recuperative power of the human brain is greatest early in life, before cerebral lateralization is complete.

According to paragraph 3, what is the relationship between cerebral lateralization and the brain’s ability to recover from injury?

AThe dominant side of a lateralized brain heals more quickly than the less preferred side heals.

BAfter cerebral lateralization is complete, the functions of injured neural circuits are almost always performed by other circuits in the same hemisphere.

CA brain that is damaged before lateralization is complete will probably lose more functionality than a brain that has already lateralized.

DIt is unlikely that a mature brain will fully recover once cerebral lateralization is complete.

 

10

What are the implications for children who fail to rely on one hemisphere or the other to perform specific functions? Leslie Tan found that four year olds who have not yet established a dominant hand are more likely than their left- or right-handed age-mates to be uncoordinated and delayed in their motor development. Other research has linked dyslexia – a serious impairment in one’s ability to read that may affect as many as 5 percent of schoolchildren in the United States – to an abnormal pattern of cerebral lateralization for visual/spatial functions. Although not everyone agrees that all forms of dyslexia have a neurological basis, many people with dyslexia do show irregularities in cerebral lateralization that may well contribute to their reading difficulties.

The word “implications” in the passage is closest in meaning to

Aconsequences

Bsolutions

Cconditions

Dreasons

 

11

What are the implications for children who fail to rely on one hemisphere or the other to perform specific functions? Leslie Tan found that four year olds who have not yet established a dominant hand are more likely than their left- or right-handed age-mates to be uncoordinated and delayed in their motor development. Other research has linked dyslexia – a serious impairment in one’s ability to read that may affect as many as 5 percent of schoolchildren in the United States – to an abnormal pattern of cerebral lateralization for visual/spatial functions. Although not everyone agrees that all forms of dyslexia have a neurological basis, many people with dyslexia do show irregularities in cerebral lateralization that may well contribute to their reading difficulties.

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

AResearch suggests that as many as 5 percent of schoolchildren in the United States may be affected by a reading disorder known as dyslexia.

BAbnormal visual/spatial functions may affect up to 5 percent of the schoolchildren in the United States who have trouble reading.

CChildren with serious impairments in their ability to read often have dyslexia or some other abnormal pattern of cerebral lateralization.

DIrregularities in cerebral lateralization have also been found among children with dyslexia, a relatively serious reading disorder.

 

12

What are the implications for children who fail to rely on one hemisphere or the other to perform specific functions? Leslie Tan found that four year olds who have not yet established a dominant hand are more likely than their left- or right-handed age-mates to be uncoordinated and delayed in their motor development. Other research has linked dyslexia – a serious impairment in one’s ability to read that may affect as many as 5 percent of schoolchildren in the United States – to an abnormal pattern of cerebral lateralization for visual/spatial functions. Although not everyone agrees that all forms of dyslexia have a neurological basis, many people with dyslexia do show irregularities in cerebral lateralization that may well contribute to their reading difficulties.

Which of the following can be inferred from the description of Leslie Tan’s research in paragraph 4?

AChildren who have not established a dominant hand by the age of four are equally likely to eventually be left-handed or right-handed.

BNot establishing a dominant hand by age four is an indication of incomplete motor development.

CIt takes longer for children to become right-handed than to become left-handed.

DDelaying the establishment of a dominant hand can increase coordination.

 

13

When do the two cerebral hemispheres being to “divide the work” and become lateralized? It was once thought that lateralization took place gradually throughout childhood and was not complete until adolescence. Now, however, it is believed that brain lateralization may originate in the prenatal period (before birth) and is clearly evidence at birth. For example, it has been noted that about two-thirds of all fetuses end up positioned in the womb with their right ear facing outward, and it is believed that this gives them a right-ear advantage and illustrates the left hemisphere’s specialization in language processing. From the first day of life, speech sounds stimulate more electrical activity in the left side of the cerebral cortex than in the

Look at the four squaresthat indicate where the following sentence could be added to the passage

This makes some sense since the majority of adults are also right-handed.

Where would the sentence best fit？Click on a square  sentence to the passage.

14

The highest brain center in humans consists to two cerebral hemispheres connected by a band of fibers

AThe role of the corpus callosum is to separate the functions of the two hemispheres to allow them to function more efficiently.

BRight handed individuals are advantaged for language and left-handed individuals are advantaged for music.

CBrain lateralization is present at birth, with different functions and different sides of the body controlled by each hemisphere.

DLateral preferences become stronger over time as the brain matures, but younger, less specialized brains recover better from injuries.

EAbout 90 percent of people maintain a consistent preference for the same hand throughout childhood, but the other 10 percent never develop a preference.

FIncomplete or irregular lateralization has been linked to development delays and reading difficulties.

 

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