Chapter 1. Brain Development: Emerging Adulthood

Synopsis

Human Development Video Activity

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You must read each slide, and complete any questions on the slide, in sequence.

cerebral cortex

The folded outer layers of the brain covering the cerebrum that are critically involved in many complex functions, such as memory, attention, perceptual awareness, thought, language, and consciousness.

limbic system

A collection of structures below the cerebral cortex that are involved in the expression and regulation of emotions that are related to self-preservation, such as fear and anger, and to the pleasures of survival behaviors, such as eating and sex.

myelination

The growth of myelin on nerve cells. The myelin coating allows nerve impulses to travel faster.

neuron

A nerve cell that receives and communicates information throughout the body as part of the central nervous system.

prefrontal cortex

The part of the brain at the front of the frontal lobe just behind the forehead. It is responsible for executive functioning, such as decision-making, reasoning, planning, impulse control, and prioritizing tasks.

senescence

The state of being old or growing old. Biological aging.

synapse

The microscopic gap across which the axon of a neuron can transfer an electrical impulse to the dendrites of an adjacent neuron.

Brain Development: Emerging Adulthood

A young professional woman in a suit working at a desk in an office with a calculator.

Author

S. Stavros Valenti, Hofstra University

Synopsis

In this activity, you will see animations and illustrations of the changes that occur in the brain during the emerging adult years between ages 18 and 25. The relationship between these biological changes and behavior in this life stage will also be explored.

REFERENCES

Spear, L. (2000). The adolescent brain and age-related behavioral manifestations. Neuroscience and Biobehavioral Reviews, 24, 417-463.

The Brain in Emerging Adulthood

A young male mechanic working on a car in a garage.

The emerging adulthood years from ages 18 to 25 is a time of excellent health, strength, stamina, and psychological well-being. All bodily systems, including the brain, function at an optimal level. However, during this period, there are some signs of a gradual physical decline due to age, and this degeneration is called senescence.

Changes in Gyri and Sulci of the Cortex

As the amount of brain tissue gradually diminishes during normal aging, there is a compensatory increase in the volume of cerebrospinal fluid causing enlargement of the ventricles.

Note: video has no audio.

Starting in the early 20s and continuing throughout adult life, there is a gradual loss of brain volume as the gyri (“hills”) of the cerebral cortex become narrower and the sulci (“valleys”) become wider. The loss of brain volume is compensated by an increase in the size of the ventricles, which are the inner chambers of the brain that are filled with cerebrospinal fluid.

Play the animation and view changes in the gyri and sulci that occur early in adulthood.

Thinning of the Gray Matter

As a general rule, normal aging is associated with loss of gray matter, but the rate of loss varies considerably between different areas of the brain.

Note: video has no audio.

It is the gray matter of the brain where neurons are concentrated and where thinning of the brain first appears in a person’s early 20s. The thinning of the gray matter is mainly due to a loss of neurons and a reduction in the number of synapses.

The rate of gray matter loss varies greatly across different areas of the brain. For example, the degeneration may occur in the frontal lobes beginning in a person’s early 20s, but the loss may not appear in the temporal lobes until after a person is in his/her 30s.

Play the animation and view the thinning of gray matter that begins in early adulthood.

Emotional Versus Intelligent Control of Behavior

A drawing showing the side view of the brain. Labels show the occipital lobe at the back of the brain, the parietal lobe toward the top back of the brain, the temporal lobe just above the brain stem at the top of the spinal cord, and the frontal lobe just behind the forehead and the front of the skull. The prefrontal cortex is a section of the frontal lobe directly behind the forehead.

^{The shift in the balance of activity between the prefrontal cortex and the limbic system begins in adolescence and continues into early adulthood. The limbic system is located deep within the brain on top of the brainstem and involves structures from the various lobes of the brain.}

You learned in an earlier activity that “the adolescent brain is a brain in flux...” (Spear, 2000, p. 238). During adolescence, synaptic rearrangement and myelination in the cerebral cortex are particularly evident in the frontal lobes that control deliberate actions and systematic thought. At the same time, there is a corresponding decrease in activity in the limbic system (within the frontal lobes), which may help to explain a gradual reduction in emotional behavior.

This shift in the balance between automatic (emotional) control and deliberate (intelligent) control extends from adolescence through emerging adulthood and beyond.

Play the animation and view the shift in the balance of activity between the limbic system and the prefrontal cortex that begins in adolescence.

The Importance of Experience

Researchers have documented changes in the brain during emerging adulthood, such as increased myelination, synaptic reduction, and rearrangement in the frontal lobes. It is likely that these changes help support a style of thought that is more practical and flexible than that of adolescence.

It is also true that young adults have much greater experience solving problems in a variety of contexts. People are more likely to make thoughtful decisions when they have encountered similar situations in the past, and they know how to avoid making hasty decisions. These mental changes are both a cause and a consequence of brain development during emerging adulthood.

Assessment: Check Your Understanding

Question 1.1

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Correct! For most people, emerging adulthood is a time of excellent health, strength, stamina, and psychological well-being.

Sorry. For most people, emerging adulthood is a time of excellent health, strength, stamina, and psychological well-being.

Assessment: Check Your Understanding

Question 1.2

QqUyJ2dKkjXEb4AttaWHX088KE89tjs1nZsbZ+eixtdUv4itBXebf9e3V4SpUVoSgTmpTcmY8vY94z6uMMCP8hIHK9LZSbFF9xjW8n2ZB6eS5w5jQYB5pHyIyV7GEZKBqnuIgTKJyiAXAhMFF3PyIlm4YJrBquYwVXMCOiLXx8p71lgOl/fkW9W47tUi+yY5u/qBlE6haQQQiZetGrWFotmVLujQzUb5VCB3J+ckft4z4U/x

Correct! When senescence begins during emerging adulthood, there is a gradual loss of brain volume as the gyri (“hills”) of the cortex become narrower and the sulci (“valleys”) become wider.

Sorry. When senescence begins during emerging adulthood, there is a gradual loss of brain volume as the gyri (“hills”) of the cortex become narrower and the sulci (“valleys”) become wider.

Assessment: Check Your Understanding

Question 1.3

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Correct! For example, the thinning of gray matter may occur in the frontal lobes beginning in a person’s early 20s, but it may not occur in the temporal lobes until after a person turns 30.

Sorry. For example, the thinning of gray matter may occur in the frontal lobes beginning in a person’s early 20s, but it may not occur in the temporal lobes until after a person turns 30.

Assessment: Check Your Understanding

Question 1.4

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Your answer should describe the brain function shift that begins in adolescence and continues through emerging adulthood. A strong limbic system functioning that promotes automatic emotional behavior during adolescence shifts to a more deliberate, practical, flexible, and systematic thinking because of the greater myelination of the cerebral cortex, especially in the frontal lobes of the brain, that takes place during emerging adulthood.

Congratulations! You have completed this activity.Total Score: x out of x points (x%) You have received a provisional score for your essay answers, which have been submitted to your instructor.