Pleasure and Pain

Question 1

What are the two major systems of human motivation?

Answer 1

the reward circuit and the punishment circuit

Together these two circuits form the behavior approach system to motivation.

Question 2

What is the evolutionary need for pleasure?

Answer 2

Pleasure serves as a reward for the body having undergone the vital functions required to stay alive.

Things like eating, drinking, responding to aggression, and reproducing all elicit pleasure as motivation to undergo these necessary life functions.

Question 3

Define:

the reward circuit

Answer 3

The reward circuit is the interconnected loop in the brain that coordinates all the various brain structures that deal with reward and pleasure.

Question 4

What are the two major centers of the reward circuit?

Answer 4

The ventral tegmental area and the nucleus accumbens

Other various brain structures involved in the circuit include the septum, the amygdala, the prefrontal cortex, and the thalamus.

Question 5

Describe the location and functions of:

the ventral tegmental area in the reward circuit

Answer 5

The ventral tegmental area (VTA) is located in the very center of the brain; it receives information about how human needs are being satisfied and communicates this information to other structures of the brain.

Question 6

What chemical messenger is used by the reward circuit?

Answer 6

dopamine

Question 7

To what brain structures does the ventral tegmental area send dopamine?

Answer 7

The ventral tegmental area sends dopamine to the following structures:

1. The nucleus accumbens
2. The amygdala
3. The septum
4. The prefrontal cortex

Question 8

What effect does an increase in dopamine have on the reward circuit?

Answer 8

An increase in dopamine causes the current behavior to be rewarded and reinforced.

Question 9

Describe the location and functions of:

the nucleus accumbens in the reward circuit

Answer 9

The nucleus accumbens is a bundle of neurons located slightly anterior to the hypothalamus; it receives reward information from the VTA, activates motor functions, and further relays the information to the prefrontal cortex.

Question 10

Describe the function of:

the prefrontal cortex in the reward circuit

Answer 10

When stimulated by dopamine from the ventral tegmental area, the prefrontal cortex responds by increasing conscious awareness and attention.

Question 11

Describe the location and function of:

the medial forebrain bundle in the reward circuit

Answer 11

The medial forebrain bundle (MFB) connects the various structures involved in the reward circuit; it helps to strengthen the association between the structures in order to promote repetition of the action.

Question 12

Describe the function of:

the punishment circuit

Answer 12

The punishment circuit enables humans to cope with unpleasant situations and avoid future painful experiences.

Question 13

What activates the punishment circuit?

Answer 13

The punishment circuit is activated by aversive stimuli that also initiate the body’s fight or flight response.

Question 14

What brain structures are involved in the punishment circuit?

Answer 14

The brain structures involved in the punishment circuit are the following:

1. The thalamus
2. The hypothalamus
3. The grey matter surrounding the cerebral aquaduct
4. The amygdala
5. The hippocampus

Question 15

What chemical messenger is used by the punishment circuit?

Answer 15

acetylcholine

Question 16

Regarding the punishment circuit, what effect does acetylcholine have on the body?

Answer 16

Acetylcholine causes the anterior pituitary gland to secrete adrenocorticotropic hormone (ACTH).

ACTH stimulates the secretion of epinephrine from the adrenal glands, in order to prepare the body for fight or flight.

Question 17

When is the behavioral inhibition system activated?

Answer 17

The behavioral inhibition system (BIS) is activated when both fight and flight seem ineffective, and the only effective response to ensure survival is to submit passively.

The BIS causes an overall inhibition of behavior, thereby working against the behavioral action system of the reward and punishment circuits.

Question 18

Which brain structure is most closely involved with drug dependency?

Answer 18

the nucleus accumbens

Question 19

What do drugs do to the level of dopamine in the body?

Answer 19

The level of dopamine increases.

An increased level of dopamine has a notable effect on the brain’s reward circuit.

Question 20

Describe the effect of drugs on:

the ventral tegmental area

Answer 20

Drugs target receptors on the VTA that cause an increase in dopamine production.

Question 21

Describe the effect of drugs on:

the prefrontal cortex

Answer 21

The prefrontal cortex modulates planning and motivating action and is controlled by dopamine. When drugs initiate an increase in dopamine, the profrontal cortex is even more stimulated, causing a rise in motivation.

Question 22

Describe the effect of drugs on:

the locus coeruleus

Answer 22

The locus coeruleus plays an important role in drug addiction, as it is stimulated when there is a lack of the drug, and causes the addict to do anything possible to obtain the feelings associated with the drug.

Question 23

What three limbic system structures are highly involved in drug dependency?

Answer 23

1. The amygdala
2. The hippocampus
3. The insular cortex

Question 24

Does the brain contain a single pain center?

Answer 24

No, the brain does not contain a single pain center. Instead, there appears to be a pain matrix, whereby many brain structures are interconnected and coordinated.

Question 25

According to modern scientists, what seems to be the purpose of pain?

Answer 25

The purpose of pain is to make a person aware that his/her body is damaged or is about to be damaged, allowing them to change his/her actions.

Question 26

Define:

nociception

Answer 26

Nociception is the sensory process that produces nerve signals that are sent to the brain as pain.

Question 27

Define:

a nociceptor

Answer 27

A nociceptor is a dense network of free nerve endings that function as the sensory receptor for pain.

Question 28

Define:

pain

Answer 28

Pain is a negative sensation felt in a particular part of the body that results from nociception.

Nociception and pain are not the same; nociception is the process by which humans feel pain.

Question 29

Describe the function of:

the reticular formation in the processing of pain

Answer 29

The reticular formation is involved with the alertness associated with pain; it alters heart rate, blood pressure, respiration rate, and other bodily functions affected by pain.

Question 30

Describe the function of:

the ventral posterolateral nucelus (VPL) of the thalamus in the processing of pain

Answer 30

The VPL projects axons to the somatosensory cortex, helping to locate and determine the intensity of pain. It also functions to relay the sense of touch to the cortex.

Question 31

Describe the function of:

the medial portion of the thalamus in the processing of pain

Answer 31

The medial portion of the thalamus projects axons to the motor cortex areas of the frontal lobe, and therefore associates pain with motor and emotional reactions.

Question 32

Describe the function of:

the intralaminar nuclei of the thalamus in the processing of pain

Answer 32

The intralaminar nuclei of the thalmus are involved with the alertness response of pain and produce the negative emotional components and the behavioral responses of pain.

The intralaminar nuclei send axons to the limbic system.

Question 33

Describe the function of:

the primary somatosensory cortex in the processing of pain

Answer 33

The primary somatosensory cortex receives axons from the VPL of the thalamus and discriminates the various properties of pain.

The primary somatosensory cortex can send axons to the seconday somatosensory cortex for further pain processing.

Question 34

Describe the function of:

the secondary somatosensory cortex in the processing of pain

Answer 34

The secondary somatosensory cortex receives axons from the primary somatosensory cortex and the thalamic nuclei; it further processes pain by recognizing and associating it with past pain.

Question 35

Define:

acute pain

Answer 35

Acute pain is an immediate sensation of pain that results from a specific, highly localized, bodily injury.

Acute pain can last anywhere from a few seconds to months, but in all cases the pain eventually fades as the illness is cured or the body heals.

Question 36

Define:

chronic pain

Answer 36

Chronic pain is a disease in which pain does not have any connection to a previous injury, and instead is a result of a variety of abnormal cellular processes.

Chronic pain can be intermittent or constant, and is extremely debilitating, vastly affecting one’s quality of life.

Question 37

Define:

neurogenic pain

Answer 37

Neurogenic pain results from damage or disease directly affecting the nerves of the nociceptive pathway.

Sensations associated with neurogenic pain include hyperalgesia and allodynia.

Question 38

Define:

hyperalgesia

Answer 38

Hyperalgesia is a sensation associated with neurogenic pain in which a stimulus causes much more pain than it normally would.

Question 39

Define:

allodynia

Answer 39

Allodynia is a sensation associated with neurogenic pain in which extremely light stimuli cause severe pain.

Question 40

Define:

psychogenic pain

Answer 40

Psychogenic pain is a physical pain that has no associated physical injury or disease; it is often a result of mental, emotional, or behavioral factors.