Physiological Mechanisms of Emotion

Think of the last time you were happy. What was it like? Did you smile? Did you laugh? How did it feel? Perhaps it was a peaceful, glowing feeling. Or maybe a blind elation, an uplifting, a soaring. What was this feeling all about?

There are some people who would not stop to ask themselves these questions for fear of somehow interfering with the feeling. They simply accept it. But psychologists must define and explain all facets of human behavior and response. Tell a psychologist that you're sad, and part of him, the human part, will understand. But the scientist in him will ask: "What do you mean by that? Tell me what you do when you are sad. What sensations does this feeling bring?"

Emotion. Emotion has two aspects: behavior and experience. Emotional behaviors are qualities of an individual that can be observed, measured, or recorded. A smile is an emotional behavior because it can be observed. Other emotional behaviors are an increase in heart rate, a frown, a scream, and a laugh. All of these behaviors may be studied while an individual is explaining his feelings.

Emotional experience includes all of the feelings of emotion. Happiness, sadness, terror, and depression are all examples of emotional experience. In order to find out about emotional experience, the scientist must ask a subject to talk about his feelings; they cannot be measured. Emotional experience does not always have to accompany emotional behavior. We might be happy without smiling or sad without crying. Indeed, there are often times when we exhibit the behavior of one emotion while experiencing an opposite emotion, as when we smile to "keep up a front."

When psychologists measure emotion, they are measuring emotional behavior. If we could describe much of our emotional behavior in terms of the physiological process of our bodies, we would have gone a long way in pinning down just what emotion is all about.

Autonomic System responses When we have an emotional experience, our bodies change. In most intense emotions, extreme happiness or extreme stress, the autonomic nervous system prepares the body for action. In stress, the sympathetic division of the autonomic nervous system sends out impulses which increase heart rate, blood pressure and respiration. The responses that maintain the body, such as digestive responses, are inhibited. The salivary glands stop secreting and the mouth feels dry. These bodily responses, however, do not cause us to "feel emotion." We can experimentally dry the mouth of a human being, speed up his heart, and increase his respiration, but he will not feel afraid. These bodily changes merely accompany the feelings that we have. When the emotional situation has passed, the responses that activate our bodies subside under the influence of the parasympathetic division of the autonomic nervous system.

Brain Structures The physiological elements of emotional behavior involve structures of the brain. The two structures that are most important in emotion are the hypothalamus and the septal area.

Both the hypothalamus and the septal area have extensive connections with other parts of the nervous system. Emotions are brought about by envirnomental occurrences as well as by the internal thinking process, so neurons from both the peripheral nervous system and the higher brain centers send impulses to the hypothalamus and the septal area.

In 1956, Olds performed a famous experiment involving a'ipleasure center" in the brains of rats. First, each rat was taught to press a bar. Then a miniature electrode was implanted in one area of the rat's hypothalamus. An apparatus was constructed so that every time the rat pressed the bar an electric stimulus was delivered to his brain. In this experimental situation, the rats would do nothing but press the bar. Up to 5,000 stimuli were self-delivered to the rats' hypothalamic areas and the animals would stop only when they dropped from exhaustion. Rats that were deprived of food and then given the choice between eating and self-stimulation always chose the stimulation. Olds interpreted the rats' behavior as responding to a pleasurable stimulus. Though the experiment was of extreme importance, the rats, of course, could not report their own feelings, and it was impossible to claim that the rats were, in fact, experiencing pleasure. Subsequent work with a few human subjects does indicate that when the hypothalamus is stimulated in certain regions a "glowing" feeling is reported.

Other studies done with hypothalamic stimulation show that this area also has something to do with rage. When Masserman (1943) stimulated an area of the hypothalamus of a cat, the animal crouched, arched its back, growled and generally appeared enraged. The cat's behavior, however, appeared to Masserman to be rather "insincere," as if only the stereotyped rage behavior were evoked, without the experience. This led Masserman to call the response "sham rage."

Investigators of the septal area have found that destruction of certain regions brings about a reaction called the septal rage syndrome. A rat with septal damage becomes vicious and irritable, attacking any moving object. Since the rage syndrome is not present with the septal area intact, it is supposed that this area has an inhibitory influence on rage.

Delgado (1956) found that stimulation of other parts of the septal area was aversive to laboratory animals. In this study the animal was allowed to terminate stimulation of the septal area by pressing a bar. it did so repeatedly. If pressing the bar stimulated this region, the animal would do so once and only once. The description of emotion is a difficult task. Advanced laboratory techniques have permitted modern psychologists to go a long way toward explaining the physiological variables affecting emotional behavior. But pinning down the nature of emotional experience, or feelings, has lagged far behind. Many experimenters feel that this will eventually be explained in physiological terms.

Recent studies on lateralization of the brain show that the cortex also has a role in emotional disorders. These studies are proving both provacative and enlightening. Hell, Nitschke, and Miller (1998) have reviewed the literature in this regard and suggest that the right hemisphere plays a role. Emotional tone of voice can be detected more easily with the right hemisphere (left ear). Nonspeech sounds (laughing and crying) are detected more easily in the right hempishere. Expression of more positive emotion appears more frequently in the right hemisphere.

Studies relating emotional disorders to hemisphere lateralization suggest that apprehension and worry are associated with the left hemisphere; but that panice and fear (arousal) are related to the right hemisphere.



Now test yourself without looking back.

1. Here are some statements made about emotional situations. Write "B" next to the statements that reflect emotional behavior. Write "E" next to the ones that reflect emotional experience.
a. "I was so scared."
b. "His heart was beating wildly."
c. "When he got out of the hospital he felt wonderful." _
d. "When given the choice, he would rather push the bar than eat."

2. In a very emotional state, which division of the autonomic nervous system becomes active?

3. What happens (increase, decrease, no change) to each of the following processes in an emotional state?
a. Heart rate _
b. Respiration_
c. Salivation

4. In different animals, the areas of the hypothalamus may have to do with:
a. pleasure.
b. rage.
c. either, but not both in one animal.
d. neither.

5. A rat will continue to press a bar if by doing so he stimulates which part of the brain?

6. What is the term used to describe an animal with all of the responses of rage exhibited in a stereotyped manner?

7. Experiments indicate that an inhibitory influence over the rage response is controlled by what area?

8. The pleasure center has been demonstrated:
a. in rats only.
b. in humans only.
c. only in the lower animals.
d. in humans as well as in lower animals.





Emotion has two aspects: behavior and experience. When a person feels happy, sad, elated, or angry, he is having an emotional experience. In an emotional state, body movements, facial movements, and internal changes represent emotional ____________________________(expenence/bahavior).
_________________________________ 2

A person who reports he feels angry may be having an emotional
_____________________________ (behavior/experience).

So far, scientists have best been able to describe emotional _____________________________________ (behavior/experience).

The part of tne autonomic nervous system that becomes active in stressful situations is the sympathetic branch. Which of the following organs are affected by the sympathetic nervous system in times of stress?
a. Heart
b. Lungs
c. Bladder
d. Adrenal glands
e. all of the above
f. none of the above
___________________________________ 6

The parasympathetic division of the autonomic system usually acts opposite to the sympathetic system. When a stressful situation subsides, which system becomes dominant? ___________________________________________________ 1

An electrode is implanted in the hypothalamus of a cat and an electric stimulus is given. The animal pulls its ears back, crouches, growls, and arches its back. The area stimulated must have something to do with which emotion?
a. Pleasure
b. Pain
c. Rage
d. Elation
_____________________________________________ 4

In some cases of hypothalamic stimulation, experimenters observe sham rage. Sham rage suggests that:
a. the area stimulated affects emotional behavior but not true emotional experience.
b. the area stimulated has nothing to do with emotion.
c. the area stimulated affects emotional experience but not emotional behavior.
_________________________________________ 7

When certain parts of the septal area of a rat are destroyed, a set of responses called the septal rage syndrome is observed. Since the rage response is present only after the septal area has been damaged, we may assume that the area destroyed normally does what to the rage response?
a. Inhibits it
b. Excites it
c. (neither)
_____________________________________ 3


1 parasympathetic
2 behavior
3 a
4 c
5 experience
6 e
7 a
8 behavior


When a rat is allowed to stimulate itself electrically in certain parts of the hypothalamus, he behaves as if he finds it pleasurable. This statement is based on the observation that:
a. the rat will avoid stimulating himself.
b. the rat will calmly go to sleep when he stimulates himself.
c. the rat will continue to stimulate himself until he drops from exhaustion
d. the rat will continue to stimulate himself unless he is offered food.
_____________________________ 4

The hypothalamus and the septal area receive stimuli originating:
a. in higher brain centers.
b. in the outside world.
c. both
d. neither


Human subjects were stimulated in an area of the hypothalamus that was known to elicit a pleasurable response from a rat. What happened?
a. They reported pleasant feelings.
b. They reported no feeling at all.
c. They reported that they were afraid.
d. They became angry.
e. They went to sleep.

________________________________________ 3

Stimulation of certain regions of the septal area has been found to be aversive. If a rat has been taught to press a bar for food and then the bar-press stimulates this region of the septal area, the rat will:
a. continue to press the bar.
b. press the bar one time but no more.
c. not eat any more food, even when offered.
d. exhibit an anger response.



1 c
2 b,c
3 a
4 c
5 b



Write "B" next to the statement that reflects emotional behavior and "E" next to the statement that reflects emotional experience. a. "His heart rate increased to 90 beats per minute._________________'

b. "When I finish this test, I'll jump for joy." __________

c. "Doris feels gloomy today."__________

d. "She screamed in terror." ___________

2. Less is known about the nature of emotional experience than about emotional____________________

3. The parasympathetic division of the autonomic nervous system is most influential in times of:
a. relative calm.
b. terror.
c. stress.
d. anger.

4. What happens to each of the following processes in an emotional state?

a. Breathing rate____________

b. Blood pressure____________

c. Adrenalin secretion_____________

5. The pleasure center is found in an area of the brain called the ________________

6. Which of these appears to inhibit rage in a rat?
a. Medulla
b. Hypothalamus
c. Septal area
d. (none of these)

7. What is sham rage?____________________________________________________________________________________________________________



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