Chapter 45. The Limbic System

Learning Objectives

hippocampus
limbic system structure involved in forming new memories
hypothalamus
limbic system structure that controls eating and other motivated behaviors, governs the body’s response to stress, and influences the endocrine system via the pituitary gland
limbic system
group of brain structures that play a role in emotion, motivation, and memory
memory
the process of remembering information that has been learned
pituitary gland
master gland of the endocrine system
thalamus
brain structure that relays sensory messages to the cortex and movement messages to the cerebellum
amygdala
limbic system structure involved in strong emotions such as aggression and fear
brainstem
lowest portion of the brain, just above spinal cord; consists of the medulla, pons, midbrain, and reticular formation
cerebral cortex
six thin layers of interconnected neurons that cover the outer surface of the brain and do most of the brain's processing
drive
a state of tension or motivational force that pushes us toward a particular type of behavior that will reduce the tension
emotion
a conscious mental state or feeling that arises spontaneously as a reaction to events
endocrine system
the body’s slow communication system, consisting of glands that release hormones
The Limbic System
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Learning Objectives:

Identify the main structures of the limbic system.

Describe the functions of the main structures of the limbic system.

Review

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Review

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1. The limbic system is a group of neural structures located above the brainstem but below the cerebral cortex. These structures wrap around the thalamus.

Review

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The image includes the limbic system. In the center of the limbic system is the thalamus. Surrounding the thalamus is a horseshoe shaped area called the hippocampus. At the end of the hippocampus is the pea-sized amygdala. Underenath the thalamus, on the opposite side of the hippocampus from the amygdala, is a small structure called the hypothalamus, under which is the small pituitary gland.

2. The most important components of the limbic system are the hypothalamus, the hippocampus, and the amygdala. These structures are involved in emotions (such as fear and aggression) and drives (such as hunger, thirst, and sexual urges).

Review

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Review

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The image includes the limbic system. In the center of the limbic system is the thalamus. Surrounding the thalamus is a horseshoe shaped area called the hippocampus. At the end of the hippocampus is the pea-sized amygdala. Underenath the thalamus, on the opposite side of the hippocampus from the amygdala, is a small structure called the hypothalamus, under which is the small pituitary gland.

3. Although the pituitary gland is part of the endocrine system, not the limbic system, it is included here because it is tightly controlled by the hypothalamus, and forms a link between the limbic system and the body’s emotional responses.

Review

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Review

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The image includes the limbic system. In the center of the limbic system is the thalamus. Surrounding the thalamus is a horseshoe shaped area called the hippocampus. At the end of the hippocampus is the pea-sized amygdala. Underenath the thalamus, on the opposite side of the hippocampus from the amygdala, is a small structure called the hypothalamus, under which is the small pituitary gland.

4. Let’s look more closely at the three most important limbic system structures. The hypothalamus monitors the body’s internal status, watching for changes in temperature, fluid or oxygen level, or energy storage. When any of these falls outside the normal range, the hypothalamus motivates an appropriate behavior (such as eating, drinking, or seeking warmth) to correct the problem.

Review

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Review

Select the NEXT button to continue with the Review.

The image includes the limbic system. In the center of the limbic system is the thalamus. Surrounding the thalamus is a horseshoe shaped area called the hippocampus. At the end of the hippocampus is the pea-sized amygdala. Underenath the thalamus, on the opposite side of the hippocampus from the amygdala, is a small structure called the hypothalamus, under which is the small pituitary gland.

5. The hippocampus seems to be essential for forming new permanent memories. Individuals with damage to the hippocampus can think and perceive the world normally, but can’t store new factual information in memory.

Review

concept_review

Review

Select the NEXT button to continue with the Review.

The image includes the limbic system. In the center of the limbic system is the thalamus. Surrounding the thalamus is a horseshoe shaped area called the hippocampus. At the end of the hippocampus is the pea-sized amygdala. Underenath the thalamus, on the opposite side of the hippocampus from the amygdala, is a small structure called the hypothalamus, under which is the small pituitary gland.

6. Finally, the amygdala is involved in emotions connected to survival—primarily fear and anger or aggression. Neural activity in the amygdala increases when a person becomes frightened at the sight of a spider or a snake, or even when viewing human faces that display an angry or fearful expression.

Practice: Exploring the Limbic System

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Practice: Exploring the Limbic System

Roll over each limbic system label to see a brief description of that brain structure.

Amygdala
Pituitary gland
Hypothalamus
Hippocampus
Function of the selected brain structure:

involved in aggression, fear, and emotional memories

master gland of the endocrine system, controlled by the hypothalamus

controls eating and other motivated behaviors

involved in learning new memories

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Note: Although the pituitary gland is part of the endocrine system, not the brain, it is controlled by the hypothalamus, which is part of the brain's limbic system.

Quiz 1

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Quiz 1

Drag each label to the appropriate brain structure. When all the labels have been placed, select the CHECK ANSWER button.

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Perhaps you should go back to review the structures in the limbic system.
Select the NEXT button and move to Quiz 2.
Pituitary gland
Hypothalamus
Hippocampus
Amygdala

Quiz 2

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Quiz 2

Match the limbic system structures with their functions by dragging each colored circle to the appropriate gray circle. When all the circles have been placed, select the CHECK ANSWER button.

Select the NEXT button and move to the Conclusion.
Perhaps you should go back to review the structures in the limbic system.
amygdala
hippocampus
hypothalamus
pituitary
involved in forming new memories
master gland of the endocrine system
involved in strong emotions such as aggression and fear
controls eating and other motivated behaviors

Conclusion

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