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Chapter 11

PSYC 211 Chapter Notes - Chapter 11: Ventromedial Prefrontal Cortex, Autonomic Nervous System, Orbitofrontal Cortex


Department
Psychology
Course Code
PSYC 211
Professor
Yogita Chudasama
Chapter
11

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Chapter 11
In the case of Mr. V, he was very intelligent and even scored in the top 5
percent of the WAIST. He clearly knew he was paralyzed and in a wheel chair
but he failed to understand its implications or understand its significance.
The fact that he was unable to hike in the woods did not figure into his plans.
An emotional response consists of 3 types of components
1. Behavioral: muscular movements that are appropriate to the situation
that elicits them
2. Autonomic: facilitate the behaviors and prove quick mobilization of
energy for vigorous movement (increase activity if sympathetic branch
and decrease activity of parasympathetic branch).
3. Hormonal: hormones secreted by glands like the adrenal medulla an
adrenal cortex reinforce the autonomic responses.
Fear
The amygdala plays a special role in physiological and behavioral reactions
to objects and situations that warn of pain, unpleasant consequences, and
signify the presence of food, water, salt, potential mates or rivals.
Single neurons in the various nuclei of the amygdala become active when
emotionally relevant stimuli are presented.
Physiology of the Amygdala:
Locates within the temporal lobes
Consists of several groups of nuclei each with different functions
The amygdala has been subdivided into approximately 12 regions, each
containing several sub-regions.
o 3 major regions: lateral nucleus, the basal nucleus, the central nucleus
Lateral Nucleus: Receives info from all regions of the neocortex (including
the ventromedial and prefrontal cortex) the thalamus and the hippocampal
formation. Sends info to the basal nucleus, the dorsal medial nucleus of the
thalamus and the ventral striatum. The LN and the BN send info to the
ventromedial prefrontal cortex and the central nucleus. The central nucleus
projects to regions of the hypothalamus, midbrain, pons and medulla.
ACTIVATION OF THE CENTRAL NUCLEUS elicits behavioral, autonomic and
hormonal responses.
o The central nucleus is the single most important part of the brain for
the expression of emotional responses provoked by aversive stimuli.
Damage to the CN reduces a wide range of emotional behaviors and
physiological responses including no longer showing fear when
confronted with stimuli paired with aversive events, lower blood
levels of stress hormones and acting more tame when handled by
humans. Monkeys with no CN show no fear of snakes. Long term
stimulation of the CN produces stress induced illnesses like gastric
ulcers.
o Loud unexpected noises, the approach of large animals, heights and
specific odors automatically activate the CN.

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o Also the ability of the animal to learn that a particular stimulus or
situation is dangerous is very important.
Conditioned emotional response: a classically conditioned response that
occurs when a neutral stimulus is followed by an aversive stimulus; usually
includes autonomic, behavioral and endocrine components such as changes
in heart rate, freezing, and secretion of stress related hormones.
o In emotional response conditioning, the animal begins to elicit the
same physiological responses to the CS that the animal would
normally show to the US. In addition, the animal will show behavioral
arrest such as freezing (a CR response).
o Research indicates the physical changes responsible for the classical
conditioning of a conditioned emotional response takes place in the
lateral nucleus of the amygdala (this is the area that communicates
with the CN which is responsible for behavioral/hormonal changes).
o The purpose of a conditioned emotional response is that it prepares
an animal to confront an aversive stimulus.
o In the lab, if the CS is presented repeatedly by itself, the previously
established CR becomes extinguished. Note that extinction does not =
forgetting. The memory for the association between the CS and the US
is not erased but rather inhibited by the ventromedial prefrontal
cortex (vmPFC) lesions of the vmPFC impair extinction. The
vmPFC also modulates the expression of fear in different
circumstances.
Research with Humans
Specific Response: A response that is aimed at terminating the painful
stimulus, like letting of something that is hurting you.
Nonspecific response: Responses elicited by the painful stimulus that are
controlled by your autonomic nervous system (like blood levels going up,
hormones being secreted etc.)
Stimulation of parts of the brain produces autonomic responses that are
often associated with fear and anxiety but that only when the amygdala was
stimulated did people also report that they actually felt afraid. Those with
lesions to the amygdala show a decrease in people’s emotional responses.
Most humans fears are acquired socially and not through firsthand
experience. This can occur by watching another person being attacked or by
seeing another person display signs of fear or through instruction.
Human studies have shown that there is an increased activity of the medial
prefrontal cortex with extinction of the conditioned response.
Damage to the amygdala interferes with the effects of emotions on memory.
Normally, when people encounter events that produce a strong emotional
response, they are more likely to remember these events. No increase in
those with Alzheimer’s disease.
Patients with amygdala damage had no trouble with musical perception
(recognizing dissonance vs. consonance) but were unable to recognize scary
music (or any music that is normally associated with fear).

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Anger, Aggression and Impulse Control
Almost all species of animals engage in aggressive behaviors, which in most
cases is species specific. Many aggressive behaviors are related to
reproduction (i.e. behavior to attract mates/defend territory to build nest
etc.)
In an aggressive situation, an animal might display:
a. Threat behaviors: postures or gestures that warn the adversary to
leave or it will become the target of the attack useful in reinforcing
social hierarchies in organized groups of animals.
b. Defensive behaviors: threat behaviors or an actual attack against the
animal that is threatening.
c. Submissive behaviors: behaviors that indicate that it accepts defeat
and will not challenge the other animal.
While engaged in attacking a member of the same species or defending itself
against the attack, an animal appears to be extremely aroused with activity of
the sympathetic branch being very high.
Predation: The attack of a member of one species on a member of another,
usually because the latter serves as food for the former. The sympathetic
nervous system is not really activated when a predator attacks because it is
not angry but rather killing as a means to an end.
The neural control of aggressive behavior is hierarchical: the perceptual
system detects the status of the environment, which activates the limbic
system, the hypothalamus and amygdala control the activity of the brain
stem circuits which controls particular muscular movements that an animal
makes in attacking or defending itself.
Investigators found that aggressive attack and predation can be elicited by
stimulation of different parts of the PAG and that the hypothalamus and the
amygdala influence those behaviors through excitatory and inhibitory
connections with it.
Three principle regions of the amygdala and two regions of the
hypothalamus affect defensive rage and predation, both of which appear to
be organized by the PAG.
Lots of evidence suggests that activity of serotonergic synapses inhibits
aggression. The destruction of seretonergic axons in the forebrain facilitates
aggressive attack.
Investigators studied the levels of 5-HIAA (a metabolite of serotonin) in
monkeys and found that those with the lowest levels of 5-HIAA were the
most likely to engage in risky behavior, picking fights with those much larger
than themselves and to show high levels of aggression. Serotonin does not
simply inhibit aggression; rather it exerts a controlling influence on risky,
which includes aggression.
Early experiences can certainly foster the development of aggressive
behavior, but studies have shown that heredity plays a significant role. They
found a higher correlation between monozygotic twins than dizygotic twins
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