Download Ch 11 lec 1

+
Stimulating Neural Activity
Numerous
techniques exist for
activating neurons in the brain.
 Electrode
stimulation
 Chemical activation through cannulae
 Photostimulation: stimulation with light
+
“Two light-sensitive proteins from unicellular
organisms have been harnessed to rapidly
activate or silence neurons. This optical remote
control allows precise, millisecond control of
neural circuits.”

ChR2 Ion Channels – photosensitive proteins channel which depolarize the
membrane when blue light is presented.

NpHR Ion Transporter – photosensitive protein channel which hyperpolarizes
the membrane when yellow light is presented.
+
Genetic Methods

Classical and conditional knockouts (KO).
 Classical KOs - the function of the gene is abolished from a very early
stage of development.
 Conditional KOs - there is either a temporal restriction (gene function is
abolished at certain premeditated time windows) or a regional
restriction (no gene function in certain brain regions)

Transgenics
 Foreign gene, e.g. human APP, is inserted into the genome

Knockins
 Specific mutations are introduced in the gene leading to a loss of activity
of the proteins encoded by the targeted gene (although the gene
expression per se is not voided as it is in KOs).

Classical or conditional
+
Assessment of Species
-Common Behaviors
Assessment
of behaviors displayed by
all members of a species
 Open-field
test – general activity
 Colony-intruder paradigm – aggression
and defensive behavior
 Elevated plus maze – anxiety
 Social interaction
 Tests of sexual behavior
+
Traditional Conditioning
Paradigms - Learning
Pavlovian
conditioning
Pairing an unconditioned stimulus with a
conditioned stimulus
 Pavlov’s dogs

Copyright © 2006 by Allyn and Bacon
+ Fear Conditioning Protocol
TRAINING
Day 1
Novel Context (CS) + Tone (CS) + Footshock(US)
CONTEXT TEST
CUE TEST
Day 2
Training Context (CS)
Tone (CS)
+
Traditional Conditioning
Paradigms - Learning
Operant
conditioning
 Reinforcement
and punishment
 Self-stimulation

Animal works for electrical stimulation
+
Seminatural Learning Paradigms
 Mimic
situations that an animal might
encounter in its natural environment
 Conditioned
taste aversion
 Pairing
something that makes an animal ill
(emetic) with a taste
 Radial
 tests
arm maze
spatial abilities
Copyright © 2006 by Allyn and Bacon
+ Seminatural Learning Paradigms
Morris
 Rat
water maze – tests spatial abilities
must find hidden platform in an opaque pool
Conditioned
defensive burying – following a
single aversive stimulus delivered from an
object, rats will spray bedding at the object
 Antianxiety
drugs decrease the amount of
burying behavior
+
Mind and
Brain
Emotion
Chapter 11
+
Chapter Overview

Emotions as Response Patterns

Fear

Anger, Aggression, and Impulse Control

Neural control of aggressive behavior

Role of 5-HT

Role of vmPFC

Hormonal control of aggressive behavior

Communication of Emotions

Feelings of Emotions
+
Emotions as Response Patterns

An emotional response consists of 3 types of components:

Behavioral


Autonomic


i.e., dog defending its territory might bark, growl attack
Mobilization of energy; activity of sympathetic branch of ANS
increase while parasympathetic activity decreases
Hormonal

Released from the adrenal medulla

Epinephrine and NE further increase blood flow to the muscles

Steroid hormones

Cause nutrients stored in the muscles to be converted to
glucose
+ Amgydala

Small, almond-shaped structure in the medial temporal lobe

Adjacent to hippocampus
+
Figure 11.1 The Amygdala
Ventral striatum
Dorsomedial nucleus
of thalamus (projects
to prefrontal cortex)
Ventromedial
Prefrontal cortex
+
Emotions as Response Patterns

Fear

Amygdala

Lateral Nucleus (LA) – receives
sensory information from neocortex,
thalamus, and hippocampus and
projects to basal, accessory basal,
and central nucleus of the amygdala.

Central Nucleus (CN) – receives
information from the basal, lateral,
and accessory basal nuclei and
projects to many brain regions
involved in emotional processes.
+
CN

Single most important part of the brain for the expression of
emotional responses provoked by aversive stimuli

Threatening stimuli increase neural activity and fos expression

Damage to CN reduces or abolishes a wide range of emotional
behaviors and physiological responses


Animals no longer show signs of fear

Act more tamely when handled

Stress hormones are lower

Less likely to develop ulcers or other forms of stress-induced
illnesses
Opposite is true with stimulation of CN
+
Emotions as Response Patterns


Some stimuli automatically activate the CN and produce fear
responses (loud noises)…but learning which stimuli are
dangerous is also very important
The most basic form of emotional learning is CER
Figure 11.3 Conditioned Responses

ear

Conditioned Emotional Response – classically conditioned fear
response.
+
Classical Conditioning

Physical changes responsible for CC occur in LA

Neurons in LA project to CN, projects to hypothalamus,
midbrain, pons and medulla

Responsible for behavioral, autonomic, and hormonal
components of conditioned emotional response
+
Extinction

Repeated presentation of the CS alone (without the aversive
stimuli), then the CR eventually disappears

Extinction is not the same as forgetting, new learning

Animal learns that the CS is no longer followed by an
aversive stimulus

Expression of CR is inhibited (memory for the association
b/w CS and aversive stimuli is not erased)

Inhibition is supplied by the medial prefrontal cortex
+
Research with Humans
 Amygdala
is involved in human emotional
responses.
 Lesions of the amygdala decrease emotional
responses.
 Lesions interfere with effects of emotions on
memory.
+
Lesions of the amygdala decrease
emotional responses.

Bechara et al., (1995) and LaBar et al., (1995) found that
people with lesions of the amygdala showed impaired
acquisition of a conditioned emotional response (similar to
rats)

Angrilli et al., (1996) found that the startle response of a man
with right amygdala damage was not augmented by an
unpleasant emotion
In both cases the amygdala plays a role in the expression of the fear response
+
 Medial
prefrontal cortex is involved in extinction of
conditioned emotional responses in humans.
+ Lesions interfere with effects of emotions on
memory.

When people encounter events that produce a strong
emotional response, they are more likely to remember that
event.

Cahill et al., (1995) studied a patient with bilateral amygdala
degeneration (patient SM)
+
Lesions interfere with effects of
emotions on memory.
Cahill et al., 1995

Told a story about a boy walking with mother on his way to
visit his father at work

Showed a series of slides during story

During one part of the story, boy was injured in a traffic
accident, and gruesome slides showed his injuries

Normal subjects – remember more details from the emotionladen part of the story

Patient SM – no increase in memory
+
Lesions interfere with effects of
emotions on memory.
fMRI studies confirm lesion data

Cahill et al., 1996




Ss (subjects) watch both neutral and emotionally arousing films
(scenes of violent crime), later asked to recall the films
fMRI showed increased activity of the right amygdala when the
subjects recalled the emotionally arousing films but not when they
recalled the neutral ones
Ss were most likely to recall the emotionally arousing films that
produced the highest level of activity in the right amygdala when
they were originally viewed
Isenberg et al., (1999)

Seeing words that denote threatening situations increases the activity
of the amygdala
Activation in human
amygdala…read words,
look at pictures
Ratings of emotional intensity of facial expressions by controls and
patient S.M.
+
Anger, Aggression, and Impulse
Control

Aggressive behaviors are species-typical, usually related to
reproductive behavior (defending territory) or self-defense

Threat behaviors are more common than actual attack

Threat Behavior – stereotypical species-typical behavior warning
another animal that it may be attacked; postures or gestures.

Defensive Behavior – species-typical behavior an animal uses to
defend itself against threat of another animal.

Submissive Behavior – stereotyped behavior shown by an animal in
response to threat by another animal.

Predation – attack of a member of another species; does not result in
same level of arousal

Predator not angry with its prey…it’s simply food and must be
killed
+
Figure 11.6 Neural Circuitry in
Defensive Behavior
Gregg and Siegel, 2001
•Series of studies using cats
showed that stimulation of
the PAG elicited attack and
predation
•Hypothalamus and
amygdala can influence
these behaviors through
connections with the PAG
+
Anger, Aggression, and Impulse
Control


Activity of serotonergic (5-HT) synapses inhibits aggression.
Destruction of serotonergic axons in the forebrain facilitates
aggressive attack.

Howell et al., 2007
 5-HT activity in monkeys (examining 5HIAA in CSF)
 High levels of 5-HIAA in CSF – increased 5-HT activity
 Young male monkeys with the lowest levels of 5-HIAA showed a
pattern of risk-taking behavior, including inappropriate
aggression
 46% of monkeys with low levels of 5-HIAA died (killed by other
monkeys)

Selective breeding of rats and foxes – tame animals (increased
levels of 5-HT and 5-HIAA
+
Anger, Aggression, and Impulse
Control

5-HT also play an inhibitory role in human aggression

Decreased 5-HIAA in CSF is associated with aggression and other
forms of antisocial behavior

Fluoxetine (Prozac) is a serotonin agonist and decreases
irritability and aggressiveness

People with at least 1 short allele for the 5-HT transporter have
higher anxiety and depression

Right amygdala of people carrying the short form of the 5-HT
transporter gene showed a higher rate of activity during task
(looking at faces expressing fear or anger)
+
Anger, Aggression, and Impulse
Control

Impulsive violence may be consequence of faulty emotional
regulation…in frustrating situations we can usually calm ourselves
down…probably due to the vmPFC

Ventromedial Prefrontal Cortex (vmPFC)

Includes medial orbitofrontal cortex and subgenual anterior
cingulate cortex.
+
Figure 11.9 The Location of the
Ventromedial Prefrontal Cortex
+
Anger, Aggression, and Impulse
Control


vmPFC
Plays a role in complex analyses of social situations.
 Serves as interface between brain mechanisms
involved in automatic emotional responses and those
involved in the control of complex behaviors
 Includes using our emotional reactions to guide our
behavior and controlling the occurrence of emotional
reactions in various social situations
 Moral judgments/dilemmas, decision making
+
Phineas Gage
+
Anger, Aggression, and Impulse
Control


Hormonal Control of Aggressive Behavior

Aggression in Males

In rodents, androgen secretion occurs prenatally, decreases, and
increases again at puberty.

Inter-male aggressiveness increases at puberty.
Organizational effects – influence development of an animal’s
sex organs and brain


Effects are permanent
Activational effects - occur later in life, after the sex organs
have developed.

ie. Hormones activate the production of sperm
+ Figure 11.13 Organizational and
Activational Effects of Testosterone
on Social Aggression
Early exposure to androgens has an organizational effect that stimulates the
development of testosterone-sensitive neural circuits that facilitate male aggression
+
Anger, Aggression, and Impulse
Control

Effects of androgens on male aggression are mediated
by Medial Preoptic Area

Implanting testosterone in the MPA reinstated intermale
aggression in castrated male rats.
+
Medial Preoptic Area
See Figure 10.18
See Figure 3.21
+
Anger, Aggression, and Impulse
Control

Males attack other males, but rarely attack females
 Discrimination between sexes based on pheromones
 Intermale aggression was abolished in mice by cutting
the vomeronasal nerve (input from vomeronasal organ)
+
Anger, Aggression, and Impulse
Control

Hormonal Control of Aggressive Behavior

Aggression in Females

Less aggressive than males.

Aggression appears to be facilitated by testosterone.

Most rodent fetuses share their mom’s uterus with brothers and
sisters – peas in a pod

A female mouse may have 0,1 or 2 brothers adjacent to her

Being next to a male increases blood levels of androgens
prenatally

Females located between 2 males had more testosterone in
their blood and, when tested as adults, showed increased
aggression
+
Anger, Aggression, and Impulse
Control

Females of some primate species are more likely to engage
in fights around the time of ovulation


Mostly with males – likely due to increased proximity to males
Increased fighting before menstruation

Females tend to attack other females
+
Anger, Aggression, and Impulse
Control - human

Boys are generally more aggressive than girls

Small, but significant increases in aggressiveness in female
twins that shared a uterus with a male, versus another female

Girls with CAH - exposed abnormally high levels of androgens
during prenatal development


Castrated male (heterosexual and homosexual) criminals tend
to show less aggression (and sex drive)


Show increased aggression
Lack controls
Athletes that take steroids (including testosterone) tend to be
aggressive

Difficult to prove – may be that more aggressive people take steroids
+
Chapter Overview

Emotions as Response Patterns

Communication of Emotions

Feelings of Emotions
+ Basic Emotions

Finite set of universal, basic emotions


Darwin (evolved)
Universality of facial expressions
+ Emotions & Facial
Expressions


Ekman et al., (1960s)
Analyzing hundreds of films and photographs
of people experiencing real emotions

Complied an atlas of facial expressions

Dr. Cal Lightman
Emotions and Facial Expression

Six primary emotions
Surprise
 Anger
 Sadness
 Disgust
 Fear
 Happiness


Naturally occurring expressions are usually
variations or combinations of basic ones
+
Additional Facial Expressions
 Amusement
 Contempt
 Contentment
 Embarrassment
 Excitement
 Guilt
 Pride
 Relief
in achievement
+ Universality of Facial Expression

Several studies
 People
of different cultures make similar
facial expression in similar situations
 People can correctly identify the emotional
significance of facial expressions displayed
by people from different cultures
+ Isolated New Guinea tribe
 Ekman
(1971)devised a list of basic emotions to test
tribesmen of Papua New Guinea.
 He
observed that members of an isolated culture
could reliably identify the expressions of emotion in
photographs of people from unfamiliar cultures

They could also ascribe facial expressions to descriptions of
situations.
 Ekman
concluded that the expressions associated
with some emotions were basic or biologically
universal to all humans
+
Communication of Emotions
 Facial
Expression of Emotions: Innate
Responses
 Young
blind children show similar facial
expressions as normal sighted children.
+ Neural Basis of the Communication
of Emotions: Recognition

Laterality of Emotional Recognition

Right hemisphere is more important for the comprehension of
emotion.

Bowers et al., 1991 found that patients with right hemisphere
damage had difficulty producing or describing mental images
of facial expressions of emotions

George et al., 1996 had Ss listen to some sentences and identify
their emotional content.

Comprehension of emotion from word meaning increased the
activity of the PFC bilaterally, the left more than the right.

Comprehension of emotion from tone of voice increased the
activity of only the right PFC.
+
Role of the Amygdala in
Recognition


Important for emotion recognition, especially for facial
expressions (of fear).

Amygdala lesions impair ability to recognize fear expression

FMRI studies show large increases in amygdala activity when
people view photographs of faces expression fear
Affective Blindsight – ability of a person who cannot see objects
in his/her blind field to accurately identify facial expressions of
emotion without conscious perception of them.
+
Amygdala and Fearful Facial
Expressions
Adolphs et al, (2005)

Computer software that exposed only parts of either a fearful or happy
facial expression to determine what regions of the face the subjects
relied on to discriminate between expressions
Results

Control subjects consistently relied on eyes to make decisions about
expression

S.M. – did not derive information from the eyes

She did not even look at the eyes of any face, regardless of emotion
+
Facial Expressions and the Amygdala

Why the specific problem with fearful expressions?

Most expressions contain other cues that can be used for
identification

Happiness – smile

Fear – increase in size of the white region (sclera) of the eyes
+
Facial Expression and the Amygdala

Amygdala appears to be an integral part of a system that
automatically directs visual attention to the eyes when
encountering any facial expressions
+
Communication of Emotions

Perception of Direction of Gaze

Important to know if another’s gaze is directed toward you or
not.

Recognition of the direction of another monkey’s gaze involves
neurons in the superior temporal sulcus (Figure 11.22).

fMRI study confirmed monkey data

Pelphrey et al., 2003 had people watch an animated cartoon
of a face. When the direction of gaze changed, increased
activity was seen in the right STS an
+
Communication of Emotions

Role of Imitation in Recognition of Emotional Expressions

Mirror neurons – neurons located in the ventral premotor
cortex and inferior parietal lobule that respond when the
individual makes a particular movement or sees another
individual making that movement

Mirror neuron system is activated when we observe facial
movements in others and may provide feedback important for
empathy
+


Disgust
Anterior insula is essential to both detection and experienced
of disgust

Imaging data

Patient with anterior insula damage
Same area of the anterior insula was activated both when Ss
viewed expressions of disgust in others and when they smelled
unpleasant odors

Additional evidence that the insula is important in disgust

Understanding the emotions of others may require stimulating and
thus mildly experiencing emotions ourselves