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Chapter 14

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Janelle Leboutillier

Chapter 14 PSYB64 Chapter 14 Emotion, Reward, Aggression, and Stress Emotion  Emotion: A combination of physical sensations and the conscious experience of a feeling  Physical sensations: rapid heartbeat which are usually unconscious  Conscious sensation: subjective experience, such as feeling scared  Valence: A positive (attractive) or negative (aversive) reaction to an object or event The Evolution of Emotion  Darwin studied facial expressions of humans and other primates and concluded that emotional expression must have evolved  Emotions have evolutionary benefits o Contribution to general arousal: brain perceives a situation requiring action, emotions provide the arousal needed to trigger a response o Manage our approach and withdrawal behaviors relative to particular environmental stimuli o Enhance survival by helping us communicate  Nonverbal communication: facial expression and body language; provide an important source of social information Expression and Recognition of Emotion Controlling Facial Expression  People pay more attention to our face, in particular to the eyes  Human infants prefer gazing at faces rather than at any other types of visual stimuli  Two cranial nerves control movement of the human face: facial nerve (cranial nerve VII) and the trigeminal nerve (cranial nerve V)  Facial nerves controls the superficial muscles attached to the skin, which are primarily responsible for facial expressions  Trigeminal nerve controls the deeper facial muscles attached to bones of the head responsible for chewing food and speaking  Facial nerve has five major branches  Facial nuclei: located on either side of the midline in the pons o Do not communicate directly with each other o Receives input from primary motor cortex located in the pre-central gyrus of the frontal lobe, and many subcortical motor areas  Upper third of face receives input from both ipsilateral and contralateral facial nerves  Lower two thirds of face are controlled by contralateral facial nerve  If motor cortex of one hemisphere is damaged, upper third of face is not affected as much (since it still receives input from ipsilateral), but lower third will be paralyzed  Two major pathways for facial expression control  One involves input from motor cortex and primarily controls voluntary expression  Second in subcortical system that is primarily responsible for spontaneous expression  Volitional (voluntary) facial paresis (paralysis): damage to primary motor cortex leading to inability to smile on command of side of the mouth contralateral to damage; however can smile spontaneously on paralyzed side of face  ^People with Parkinson’s have the opposite situation (Emotional facial paresis) Biological Influence on Emotional Expression Chapter 14 PSYB64  Major emotional expressions appear to be universal across human cultures (anger, sadness, fear etc.)  Children’s capacities for emotional expression and recognition develop according to fairly regular timeline with little influence by experience (supports Darwins theories)  Monozygotic twins are more similar than dizygotic twins in age at which they begin to show fear of strangers  Monkeys secluded from other monkeys still developed fear response as unisolated monkeys Environmental Influence on Emotion  Influences of culture and learning modify emotional expression o Medical doctors undergo training to withhold emotions (disgust) that would be inappropriate to express to patients  Presence of other people influences the intensity of emotional expression  Blind babies exhibit social smiles at the same age as sighted infants (3 months) o But by adulthood there are differences in emotional expressions  Congenitally blind adults show same number of facial expressions as sighted adults o Observers have difficulty interpreting their expressions (blind) Individual Differences in Emotion  Individuals are different from others in their overall levels of emotional reactivity  Newborn infants show consistent levels of reactivity to unpleasant odor  Infant who are highly reactive to environmental stimuli are at greater risk for anxiety and mood disorders later in life  Extremely low-reactive infants  anti-social later in life  Amygdala is a source of individual differences o Plays a crucial role in interpretation of emotional stimuli  People with major depressive disorder show higher levels of activity in amygdala Can We Spot a Liar?  Deliberate lying is difficult because it requires a great deal of short-term memory o Therefore people who deliberately lye slip in predictable ways  Add ‘ums’ and ‘uhs;  Stiffen the head and upper body  Nod their heads less frequently and do not use hand gestures as much when they’re telling the truth  Inappropriate smiling and laughing caused by nervousness  Swinging feet  Lack of eye contact in Western cultures is seen as a sign of dishonestly but other cultures eye contact is seen as dominant and impolite expression  Polygraph: lie detector o Used in law enforcement but can be unreliable o Data reflects arousal and innocent people are usually aroused out of fear of being accused  fMRIs may be used in future to detect changes in brain activity during lying  Brain fingerprinting: EEG recording are used to determine recognition of crime scene evidence  ^These technologies raise ethical and privacy issues Theories of Emotion  Three theories that try to characterize the relationships between physiological experience and a conscious, subjective experience of feeling (two components of emotion) Chapter 14 PSYB64 The James-Lange Theory  Theory suggests that a sequence of events results in an emotional experience and an awareness of our physical state leads to identification of a subjective feeling o Different states are so distinct we can label them (happy is diff. from sad)  We do not do a very good job of discriminating between fear and sexual arousal  Theory also suggests that our facial expressions affect the way we feel o Intentionally making facial movements can stimulate physical responses that are similar to spontaneous emotional expression  Empathy: ability to understand another person’s feelings o Imitating the facial expression of others might contribute to empathy  Expression of an emotion increases its intensity o We think that crying would make us feel better o People think that holding anger inside will make it worse o These ideas come from the idea of catharsis  Catharsis: emotions are viewed as filling a reservoir; when reservoir is full, the emotions will ‘overflow’ emptying the person of that emotion  Expressing an emotion is more likely to enhance than reduce your feelings The Cannon-Bard Theory  Proposes that both the subjective and physical responses occur simultaneously and independently  CNS has the ability to produce an emotion directly, without needing feedback from the PNS  PAGE 411 for difference between two theories The Schachter-Singer Theory  Assumes that emotions result from a sequence of events  This theory does not require a specific set of physical responses for each emotions  Instead of a stimulus first produces general arousal  Once aroused, we make a conscious, cognitive appraisal of our circumstances which allows us to identify our subjective feelings  Arousal might lead to several interpretations based on the way a person assesses his or her situations  Weakness of theory: assumption that physiological states are not uniquely associated with specific emotions Contemporary Theories of Emotion  Physical responses associated with an emotion may range from quite specific to quite ambiguous  Emotional stimuli can produce overlapping physical responses such as anger or fear  Initial specificity of the physical response leads to unambiguous recognition by the cerebral cortex (seen in James and Lange theory)  The least differentiated physical signals will produce arousal which will require sig. cognitive processing and evaluation (seen in Schachter- Singer theory) o Correctly predicts emotional responses may range from immediate to delayed based on amount of cognitive processing that is required  PAGE 412 DIAGRAM  A stimulus is processed by the sensory cortex if it is immediately present, or by the hippocampus if the stimulus is remembered  Then these areas activate structures involved with emotion such as the brainstem, hypothalamus, amygdala  Messages are sent to ANS and to higher levels of the brain  Somatosensory cortex encodes this entire this entire pattern of experience ∨ Chapter 14 PSYB64  Somatic marker: An association formed between stimuli and resulting patters of physical activation  Ventromedial prefrontal cortex forms associations between somatic markers and facts about the situations elicited them o If these same situations reappear, the brain would reactivate appropriate somatic marker o Somatic markers provide a way for the brain to map features of the external world in terms of the changes they stimulate in the body, coloring situations as positive or negative  Patients with frontal lobe damage can easily describe graphic images of sex and violence they are show, but are unable to tap into somatic markers that would provide them with normal emotional response to these stimuli Biological Correlates of Emotion  Emotional states are accompanied by complex, interacting physical responses that usually combine activation of the ANS, amygdala, cingulate cortex and cerebral cortex The Autonomic Nervous System  ANs participates in the general arousal associated with emotional states  Sympathetic division of the ANs is responsible for our fight-or-flight response  Parasympathetic division participates I resting activities (digesting, body tissue repair)  ANS answer primarily to the hypothalamus (directly or by way of nucleus of solitary tract)  Solitary tract is a structure located in medulla that receives input from hypothalamus and participates in ANS control  During different emotional states certain autonomic function (hear rate, finger temperature, skin conductance, muscle activity) produce different patterns o Degree and reliability of these observations remains a dispute  Autonomic response associated with negative emotions appear stronger than those associated with positive emotions The Amygdala  Removal of temporal lobes can lead to less intense emotions o Appear oblivious to fearful situations o More frequent and inappropriate sexual behaviors o Overly reactive to visual stimuli o Failure to recognize familiar objects o Kluver - Bucy syndrome^ o Studies in Rhesus monkeys  Amygdala is composed of three clusters of nuclei  Different parts participate in emotion, reward, motivation, learning, memory, attention  Amygdala receive info from other areas of neo-cortex (esp. sensory cortex, cingulate cortex and hippocampus)  Amygdala projects widely to diff areas of the brain (incl. frontal and temporal lobes of cortex, olfactory bulb and cortex, basal ganglia, hypothalamus, nucleus accumbens)  Urbach-Wiethe disease: destroyed amygdala conditions; difficulty identifying or knowing how certain emotions are expressed  Autistic people have serious difficulties identifying emotions of other people (particularly fear) o Fail to make eye contact with others o Have shown to have abnormalities in the amygdala  Fear circuit: a pathway connecting the amygdala with the thalamus which receives sig. input from most-sensory system en route to the cortex o Provides rapid evaluation of emotional significance of a stimulus Chapter 14 PSYB64  Amygdala plays a role in classical conditioning of fear  Damage to amygdala interrupts previously learned fear responses and prevent further learning of new danger  Classical conditioning to fear is independent of cerebral cortex and is taken care of by thalamus- amygdala circuit  Amygdala has a large number of benzodiazepine receptors which are major tranquilizers used to reduce anxiety (Valium) o Suggests that amygdala plays a role in processing negative emotions The Cingulate Cortex  Serves as a gateway between amygdala, other limbic structures and the frontal lobes of the cerebral cortex  Anterio
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