Emotion

Purves et al., Chapter 29 (and part of Chapter 21) (and Chap 25 figure, Chap 17 figure)

General - historical

Darwin - Expression of emotion in man and animals - 1872
James-Lange theory: physiological changes -> emotional experience "we are afraid because we tremble" counterintuitive
Cannon-Bard theory: emotional experience is primary (Cannon coined "fight or flight") (and, of course, it is the sympathetic nervous system that prepares the body for both)

Hypothalamus

Fig. 29.1
Bard did experiment implying that cortex inhibits hypothalamic (sham - directed at everything) rage unless the caudal hypothalamus is also disrupted.
Hypothalamus -> reticular formation for rage
Walter Hess (1949 Nobel prize) - rage or fear if hypothalamus stimulated.
(shared with Moniz who developed frontal lobotomy)
not in book: Electrical self-stimulation (Olds and Milner) - of hypothalamus is positive reinforcement in operant conditioning paradigm in a Skinner box

Fig Box 21A
hypothalamus
surprisingly not in book: Lesions to ventromedial nucleus makes a fat rat, so older literature called this a satiety center, lesions to lateral hypothalamus makes a thin rat, so LH was once called a hunger center. There are problems with calling a small lesioned area a such-and-such-center based on the defect. Also, LH is where medial forebrain (reward) system goes (dopamine, covered repeatedly already).

Facial expression of emotion

Fig Chap 29 Box A
block diagram
Interesting story - voluntary facial paresis inability to volontarily move lower facial muscles on one side due to lesion [pyramidal smile]

Fig. Box B Chapter 17

Fig Chap 29 Box A
Photos to demonstrate above
Duchenne (1862) cannot will certain spontaneous smiles
Inability is over-riden (symmetrical) in involuntary movement ["Duchenne smile"] as hypothalamus and amygdala feed to reticular formation and hence to motor neurons.

Fig Chap 28 Box A
Duchenne demonstration, electrical stimulation of face ("faradization") mimics emotional expressions.

Brain areas

Limbic system
Started with Broca (1879)- limbic = "border"

Fig. 29.3
Fig. 29.4
Limbic system
Papez (1937) circuit
Note that in sheep brain tract dissection, the fornix and mammillo-thalamic tract were shown in slide 11

rabies affects hippocampus - exxagerated fear etc.
tumors in cingulate cortex - fear & other emotions

Figs A & B, etc., Box 29B
Amygdala
Amygdala connects to hypothalamus so it is related to the Papez (limbic) circuit.
lesions - fearlessness, difficulty recognizing emotions
stimulation - fear and violence

Box C (no figure)
Kluver-Bucy syndrome with amygdala lesion.
A terribly hostile monkey becomes docile with temporal lobe lesion (loss of fear) - hypersexuality, mouthing objects, etc.

Box D
Patient SM has degeneration of amygdala - cannot recognize or draw fear
Urbach-Wiethe disease (autosomal recessive)

Interesting stories:

Fig (not in 4th edition)
Lesions can be big- Phineas Gage - spike through brain then acted oddly (is it any wonder?)
Aprosody - inability to express emotion (like with monotone) with suprasylvian parietal cortex (on right side)

Box E - Affective disorders
Lincoln "I am now the most miserable man living...I must die or be better, it appears to me,"
Depression (counting several categories) will affect 10 % of people.
Relieved by lots of drugs, fluoxetine (brand name Prozac) [serotonin uptake inhibitor] widely prescribed likened to "soma" in Aldous Huxley's "Brave New World" Late 1980's, now one of the most prescribed drugs. Also sertraline (Zoloft) and paroxetine (Paxil)
Depression more common in females
Other coverage of depression in transmitters outline
and in "alumnus e-interview."

Exam questions from 2005 - 2007 relating to this outline

What is the main motor nerve to control facial expression?

facial (7)

Why would paralysis be a more likely consequence of stroke in the lower portion of the face than in the upper portion?

upper is bilaterally innervated, lower is not

Lesions to the lateral hypothalamus resulted in a thin rat, and so the lateral hypothalamus was referred to as a hunger center. An alternative interpretion involved the disruption of
what system involved in affect and motivation?

interrupt dopaminergic motivational tract

What part of the cerebral cortex is in the limbic system?

cingulate

Dopamine comes to the caudate from what brain structure?

substantia nigra

With brain cuts in and around the hypothalamus and with stimulations of the hypothalamus, Bard and (the Nobel prize-winning) Hess (respectively) studied what process?

rage (emotion)

Under what circumstances would a rat give itself electrical stimulation of the brain?

electrode in hypothalamus, stimulation is reinforcement (reward), will press bar in Skinner box

In voluntary facial paresis, a person with unilateral damage to fibers from the motor cortes, the smile will be crooked. Under what circumstances will the same person give a symmetrical smile?

a spontaneous smile resulting from humor

What happens to a monkey with a lesion in the amygdala?

get less aggressive, hypersexual

Why is it an oversimplification to call the lateral hypothalamus a hunger center on the basis of lesion experiments?

there are logical problems, also the medial forebrain bundle traverses the LH, and it has many controls on motivation

In the many functions attributed to the limbic system, what function did Kluver & Bucy attribute to the amygdala?

mood on a scale from cuddly to ferocious

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This page was last updated 3/28/08