Emotions

Emotions• Emotions consist of patterns of physiological

responses and species typical behaviors• In humans these responses are accompanied

by feelings• Feelings + appropriate behavior = Emotions

Emotions as response patterns

• an emotions responses consists of three types

of components

1. Behavioral components

2. Autonomic responses

3. Hormonal responses

Behavioral components

• The behavioral component consists of muscular movements that are appropriate to the situation that elicits them

• For example, a dog defending its territory against an intruder first adopts an aggressive posture , growls, and shows its teeth

• If the intruders do not leave, the defender runs toward it and attacks

Autonomic responses

• Autonomic responses facilitate the behaviors and provide quick mobilization of energy for vigorous movement

• The activity of the sympathetic branch increase while that of the parasympathetic branch decreases

• As a consequence, the heart rate increases, and change in the size of blood vessels shunt the circulation of blood away from the digestive organs toward the muscles

Hormonal responses• Hormonal responses reinforce the autonomic

responses • The hormones secretes by the adrenal medulla,

epinephrine and nor epinephrine , increase blood flow to the muscles and cause nutrients stored in the muscles to be convert into glucose

• The adrenal cortex secretes steroids hormones, which also help to make glucose available to the muscles

Categories of emotions

Fear • The integration of the components of fear appears

to be controlled by the amygdala• Location: The amygdala is located within the

temporal lobes• Functions: It play a special role in physiological and

behavioral reactions to objects and situations that have special biological significance, such as those that warn of pain or other unpleasant consequences or signify the presence of food, water, salt, potential mates or rivals, or infants in need of care

Fear The amydala has been divided into approximately twelve regions Various nuclei of the amygdala become active when emotionally relevant

stimuli are presented Major regions of the amygdala

• Medial nucleus – receives sensory input, including info about the presence of odors, and relays it to the medial basal forebrain and hypothalamus

• Lateral nucleus (LA) – receives sensory info from the primary somatosensory cortex, association Cortex, thalamus and hippocampus formation; sends projections to basal, accessory basal, and central nucleus of the amygdala

• Central nucleus (CE) – region of the amygdala that receives sensory info from the basal, lateral, and accessory basal nuclei and projects to a wide variety of regions in the brain; involved in emotional responses;

• The CE project to regions of the hypothalamus, midbrain, pons , and medulla that are responsible for the various component of emotional responses

Aversive stimuli• The central nucleus of the amygdala is the single most

important part of brain for the expression of emotional responses provoked by aversive stimulus.

• When threatening stimuli are presented, both the neural activity of the central nucleus and the production of FOS protein increase.

• Conditioned emotional response – a classically conditioned response that occurs when a neutral stimulus (e.g. bell) is followed by an aversive stimulus (e.g. shock); usually included autonomic, behavioral, and endocrine components such as changes in heart rate, freezing, and secretion of stress-related hormones

• However, if an organism can learn a coping response (a response that terminates, avoids, or minimizes an aversive stimulus), the emotional responses will not occur

• CE necessary for development of a conditioned emotional response

Damage to the central nucleus• Damage to central nucleus( or to the nuclei that provide it

with sensory information) reduce or abolishes a wide range of emotional behaviors and physiological responses

• After damage, animals no longer show sign of fear when confronted with stimuli that have been paired with aversive events

• Ledoux and his colleagues have shown that the central nucleus is necessary for the development of a conditioned emotional response

• If this nucleus is destroyed, conditioning does not take place

Research with human• Lesion of the amygdala decrease people’s

emotional responses.• Studies: Two studies found that people with

lesions of the amygdala showed impaired acquisition of a conditioned emotional response, just as rats do

• Effects on memory: Damage to the amygdala also interferes with the effects of emotions on memory

• Studies : Mori et al.(1999) questioned patients with Alzheimer’s disease who had witnessed

Cont… the devastating earthquake that struck Kobe ,

Japan, in 1955• They found that memory of this frightening

events was inversely correlated with amygdala damage

• The more a patient’s amygdala was degenerated, the less likely it was that the patient remembered the earthquake

Amygdala activity toward emotional responses

• Several imaging studies have shown that the human amygdala participates in emotional responses

• Cahill et al.(1996) had people watch both neutral and emotionally arousing films( such as scenes of violent crime)

• Later, the experimenters placed the subjects in a PET scanner and asked them to recall the film

• The activity of the right amygdala increased while the subject recalled the emotionally arousing films but not when they recalled the neutral ones

Anger and aggression• Species-typical behaviors• Many related to reproduction (e.g. gain access to mate)• Threat behaviors – a stereotypical species-typical behavior

that warns another animal that it may be attacked if it does not flee or show a submissive behavior; displayed more often than actual attacks

• Defensive behaviors – a species-typical behavior by which an animal defends itself against the threat of another animal

• Submissive behaviors – a stereotyped behavior shown by an animal in response to threat behavior by another animal; serves to prevent an attack

• Predation – attack of one animal directed at an individual of another species on which the attacking animals normally preys

Neural control of aggressive behavior• Periaqueductal grey matter: The PAG of the

mid brain appears to be involved in defensive behavior and predation. These mechanisms are modulated by the hypothalamus and amygdala

Role of serotonin• Several studies have found that serotonergic

neurons play an inhibitory role in human aggression

• A depressed rate of serotonin release ( indicated by low levels of 5-HIAA in the CSF) are associated with aggression and other forms of antisocial behavior, including assault, arson, murder, and child beating

• Coccaro et al. (1994) studied a group of men with personality disorder(including history of impulsive aggression) with the lowest serotonergic activity

Treatment• If low level of serotonin release contribute to

aggression, drugs that act as serotonin agonists might help to reduce antisocial behavior

• Coccaro and kavoussi(1997) found that Fluoxetine (Prozac), a serotonin agonist, decreased irritability and aggressiveness, as measured by a psychological test

Orbit frontal cortex• Location: It is located at the base of the frontal

lobes and covers the part of the brain just above the orbits( the bones that form the eye sockets hence the term orbito frontal

• Its inputs provide it with info about what is happening in the env’t and what plans are being made by the rest of the frontal lobes, and its outputs permit it to affect a variety of behaviors and physiological responses

Prefrontal cortex

• The prefrontal cortex plays an important role in regulation of emotional expression, including anger and aggression

• In a laboratory setting, anger activates this region

• Violent criminals generally show a low level of activity of this region, and the volume of gray matter in this region was lower than normal in a group of people with antisocial personality disorder

Role of serotonin• The release of serotonin in the prefrontal

cortex activates this region, and some investigators believe that the serotonergic input to this region is responsible for the ability of serotonin to inhibit aggression and risky behavior

• Low 5-HIAA low level of serotonin low activity in prefrontal cortex high level of aggression

Communication of emotions

How to communicate emotions

Means of communication of emotions

2) Facial expressions

3) Non verbal sounds

Facial expression of emotions

Innate responsesBy CHARLES DARWIN

CHARLES DARWIN

CHARLES DARWIN AND EMOTIONS

• Human expressions of emotions evolved from similar expressions in other animals.

• Emotional expressions are innate, unlearned responses consisting of a complex set of movements , principally of the facial muscles.

Charles Darwin

• Obtained evidence by observing his own children.

• Also studied across culture• Words used may be different because of

developing different languages but the emotional expressions are the same.

• People in different cultures used the same pattern of movements of facial muscles to express a particular emotional state.

research

• By EKMAN and his colleagues• Confirm Darwin hypothesis that facial

expressions of emotions uses an innate, species typical repertoire of movements of facial expressions.

• Studied an isolated tribe in new guinea

research

• Conclusion: expressions were unlearned behavioral

patterns. Different cultures use different words but

the facial expressions are the same. words must be learned and not innate.

research

• Compared the facial expressions of blind and normally sighted children.

• If expressions of two groups are similar than the expressions are natural and do not require learning by imitation.

• Results confirmed the naturalness of expressions.

Neural basis of communication of emotions

Communication a two way process

research

• By kraut and johnston unobtrusively measured people in

circumstances that would be likely to make them happy.

Only small signs of happiness when alone but more happiness when interacting with other.

Even 10 month infants showed this tendency.

Emotional recognition and brain

• Right hemisphere plays an important role in comprehension of emotions.

• High activity of pre frontal cortex• Comprehension of emotion only by tone of

voice increased the right pre frontal cortex activity

Pure word deafness

• Caused by damage to the left temporal cortex

• The man could not comprehend the meaning of speech but had no difficulty identifying the emotions being expressed by its intonation.

Role of amygdala in emotional recognition

• Role in emotional responses• Role in emotional recognition• Lesions of the amygdala impair peoples ability

to recognize facial expressions of emotions, esp. expression of fear.

• High activity of amygdala in cases of fear • Only small increases in case of happiness

Continued…

• Lesions don’t appear to affect people’s ability to recognize emotions in tone of voice.

• Amygdala receives visual info that we use to recognize facial expressions of emotions directly from the thalamus and not from the visual association cortex.

• Amygdala receives visual info from two sources:• 1) sub cortical• 2) cortical

Cont….

• The superior colliculus and pulvinar( a large nucleus in the posterior thalamus) gives input to the sub cortical and because of this even some people with blindness caused by damage to the visual cortex can recognize facial expressions.

IMITATION

Role of imitation

• Somatosensory cortex

When we see some one making an expression, we imagine our own self making the same expression.

Moebius syndrome

Cont….

• Defective development of 6th and 7th cranial nerves and results in facial paralysis and inability to make lateral eye movements.

• Bec of this defect cannot make facial expressions of emotions.

• Difficulty in recognizing the facial expressions of other people

• Their inability to produce facial expression of emotions makes it impossible for them to imitate the expression of other people.

DISGUST

CONT…

• Damage to the insular cortex and basal ganglia• Expression of disgust activates the insular

cortex• The insula contains the primary gustatory

cortex, so it is also involved in recognition of bad taste.