+ stimulating neural activity numerous techniques exist for activating neurons in the brain....

+Stimulating Neural Activity

Numerous techniques exist for activating neurons in the brain.Electrode stimulationChemical activation through cannulaePhotostimulation: 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 speciesOpen-field test – general activityColony-intruder paradigm – aggression

and defensive behaviorElevated plus maze – anxietySocial interactionTests 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

CUE TEST

Tone (CS)

TRAINING

Novel Context (CS) + Tone (CS) + Footshock(US)

Day 1

CONTEXT TEST

Training Context (CS)

Day 2

+Traditional Conditioning Paradigms - Learning

Operant conditioningReinforcement and punishmentSelf-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 arm maze tests spatial abilities

Copyright © 2006 by Allyn and Bacon

+Seminatural Learning Paradigms

Morris water maze – tests spatial abilitiesRat 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

+

Emotion

Chapter 11

Mind and Brain

+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

i.e., dog defending its territory might bark, growl attack Autonomic

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

Ventromedial Prefrontal cortex

Ventral striatumDorsomedial nucleus of thalamus (projects to 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

ear Conditioned Emotional Response – classically conditioned

fear response.

Figure 11.3 Conditioned Responses

+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)


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 emotion-laden part of the story

Patient SM – no increase in 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


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


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)


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


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


Effects of androgens on male aggression are mediated by Medial Preoptic Area

Implanting testosterone in the MPA reinstated intermale aggression in castrated male rats.

+

See Figure 10.18 See Figure 3.21

Medial Preoptic Area


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)


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


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 Show increased aggression

Castrated male (heterosexual and homosexual) criminals tend to show less aggression (and sex drive) 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

SurpriseAngerSadnessDisgust FearHappiness

Naturally occurring expressions are usually variations or combinations of basic ones

+Additional Facial Expressions

Amusement

Contempt

Contentment

Embarrassment

Excitement

Guilt

Pride in achievement

Relief

Satisfaction

Sensory pleasure

Shame

+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


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


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

+ stimulating neural activity numerous techniques exist for activating neurons in the brain....

Documents

light slide

brain slide

conditional slide

bacon slide

burying behavior slide

electrical stimulation

gene expression

targeted gene