Lecture 19 - Emotions (1) PDF

Introduction to Behavioral Neuroscience PSYC 211 Lecture 19 of 24 – Emotions Textbook Chapter 14 Professor Jonathan Britt Questions? Concerns? Please write to [email protected]  EMOTIONS Emotions exist in...

Introduction to Behavioral Neuroscience PSYC 211 Lecture 19 of 24 – Emotions Textbook Chapter 14 Professor Jonathan Britt Questions? Concerns? Please write to [email protected]  EMOTIONS Emotions exist in the abstract: You can cognitively think about emotions and make your face artificially express specific emotions (like when people tell you to smile or to try to look sad). - This aspect of emotions is processed in the neocortex Emotions also exist as a raw reflexive feeling. - This aspect of emotions is processed in the limbic system. For example, the emotion of fear typically requires a functional amygdala. Sensory inputs clearly diverge into multiple pathways. - Streams of thought are processed in the cerebral cortex. - Streams of feeling are processed in the limbic system. The biological details are largely unknown. WHEEL OF EMOTIONS WHEEL OF EMOTIONS  EXPRESSION OF EMOTION Facial expressions of emotion are innate, natural, unlearned responses involving complex muscles movements. Babies as young as 36 hours display universal facial expressions.  EXPRESSION OF EMOTION Many animals broadcast their emotions with changes in posture, facial expressions, and nonverbal sounds (such as sighs, moans, and growls). Facial expressions of emotion are often reduced when people are alone. People can reliably discriminate between six different classes of facial expression: fear, anger, surprise, disgusted, sad, and happy. Recognizing emotions through their facial expressions is generally automatic, rapid, and fairly accurate. When people are given more time to think about the emotion conveyed by facial expressions, they tend to show very little improvement.  ABILITY VERSUS MOTIVATION In social situations, some people can identify the emotions of others in automatic, easy, straightforward manner. However, this skill does not come naturally to many people, and this is a source of frustration because it is obviously helpful to be able to automatically intuit the emotions of others. An inability to recognize the emotions of others is often mistaken as a lack of interest in other people or a conscious disregard for the emotions of other people. Just because a skill doesn’t come naturally to someone, that doesn’t mean they don’t care about it. They often care about it more than most people because they actively struggle with the activity, unlike everyone else. It is something they have to work at, which is very frustrating.  EXPRESSION OF EMOTION The ability to display emotions and recognize them in others transcends cultural and linguistic barriers (to some extent). There are no differences in the display of emotional facial expressions between congenitally blind, non-congenitally blind, and sighted athletes after winning and losing games. An isolated tribe in New Guinea had no trouble recognizing emotional expressions in westerners, and westerners had no trouble recognizing emotional expressions in them.  EXPRESSION OF EMOTION Genuine, automatic, involuntary facial expressions sometimes involve different facial muscles than artificial expressions of emotions do. This is why actors often try to experience real emotions on set, rather faking them. Volitional facial paresis is a condition where people cannot voluntarily control their facial muscles (due to damage in or around primary motor cortex), but they can still express genuine emotions, even when the same muscles are involved. Emotional facial paresis is a condition where people do not show automatic facial expressions of emotion, but they have no trouble voluntarily moving facial muscles. This is often seen in Parkinson’s Disease, where there is degeneration of subcortical structures. Volitional facial paresis Emotional facial paresis told to smile vs told a joke told to smile vs told a joke  ASSESSING FEAR IN ANIMALS Snake Spider Neutral Monkeys react to candy placed next to a snake, spider, or neutral object. Researchers assess their fear by measuring time to food-retrieval, among other variables. Raw emotional feelings are coupled to various behavioural and physiological responses Behavioral responses consists of muscular movements (facial expressions, choreographed movements, body language). Autonomic responses (signaling through peripheral nervous system) facilitate fight or flight behaviors and provide quick mobilization of energy for vigorous movement. Hormonal responses (signaling through blood) reinforce the autonomic responses. INTRACRANIAL SELF-STIMULATION SEXUAL BEHAVIOUR CIRCUITRY  READING EMOTIONS IS MORE OF AN ART THAN A SCIENCE People increasingly argue that the old literature overstates the case for the universality of recognizing emotion in facial expressions. Emotional facial expressions are not super specific. The same facial expression can convey different emotions, and different facial expressions can convey the same emotion. Inferring emotions from facial expressions is not very reliable. The same emotion is not reliably expressed through nor perceived from a common set of facial movements. The generalizability (contextual and cultural effects) of deducing emotions from facial expressions is not well studied. Overall, emotional experiences do not reduce to six different type of emotions. There seems to be about 25 unique emotional blends, and they do not manifest in prototypical facial-muscle configurations alone, but rather in multimodal behavioural expressions involving voice, touch, posture, gaze, and head/body movements. THEORY OF EMOTION 1. Perception of an emotion-eliciting event (e.g., see a spider). 2. Subjective feelings of emotion (e.g., fear). 3. Behavioral and physiological responses (e.g., trembling, sweating and running away). The common-sense view is that the subjective feelings of emotion precede and cause the associated physiological response.  EARLY RESEARCH In the late 1800s there were reports that people with spinal cord damage felt emotions less intensely than before their accident. The reduction in emotional experiences correlated with how much sensation the people had lost (how paralyzed they were, which corresponds to the location of the spinal cord damage). Some subjects looked and acted angry at times, but they reported that they did not feel very angry. JAMES-LANGE THEORY 1. Perception of emotion-eliciting event (e.g., see a spider). 2. A collection of behavioural and physiological responses are triggered (e.g., trembling, sweating, increased heart rate). 3. Feedback from the peripheral nervous system to the brain triggers subjective feelings of emotion (e.g., fear).  JAMES-LANGE THEORY Interfering with the muscular movement associated with a particular emotion slightly decreases people's ability to experience that emotion. This has been reported following botox injections into the face to reduce wrinkles. However, …  Our internal organs are relatively insensitive and do not respond quickly enough to account for our emotional feelings.  Cutting the sensory nerves between the internal organs and the central nervous system does not abolish emotional behaviour in animals.  Injecting hormones or artificially activating the autonomic nervous system does not reliably or consistently produce specific emotions.  THE LIMBIC SYSTEM The cingulate cortex is a large area that overlies the corpus callosum. Cingulate means encircling. This region interconnects many limbic areas of the brain. The hippocampus and amygdala are in the temporal lobe of the cerebral cortex. They each contain several distinct nuclei. The hippocampus is critical for explicit memory formation. The amygdala is critical for feeling and recognizing emotions, particularly fear. (The mammillary bodies, septum, and fornix are also part of the limbic system.) IDENTIFYING EMOTIONS IN OTHERS Patient S.P. received a bilateral amygdalectomy to treat a seizure disorder. Afterwards she no longer experienced any fear. She had no trouble recognizing specific faces in photographs, but she could not identify when the face expressed fear. She had not trouble generating artificial expressions of emotion (including fear), but she could not even identify the emotion of fear in photos of herself. To a lesser extent, but still significant, she also had diminished ability to recognize disgust, sadness, and happiness. Her ability to detect surprise and anger were unimpaired.  Eye movements of control subject vs patient RECOGNITION OF EMOTION: EYE MOVEMENTS AND FIXATIONS People tend to spontaneously look at and examine the eyes of faces to detect the emotional state of the person they are interacting with. S.M. is a patient with bilateral amygdala damage. When shown photographs of faces, she doesn’t naturally look at the eyes. S.M. got better at recognizing emotions in photos after she was taught to examine the eyes, but she had to be repeatedly reminded to look at the eyes.  CENTRAL NUCLEUS OF THE AMYGDALA The central nucleus of the amygdala regulates emotional responses, especially fear. Lesions of the central nucleus reduce/eliminate innate and learned fear responses (all aspects of fear: behavioural, autonomic, and hormonal). Yet, fear of suffocation is normal (or heightened) in people with bilateral amygdala damage. Stimulation of the central nucleus causes fear, anxiety, and agitation. Persistent stimulation can promote stress induced illnesses (e.g., ulcers). Viewing threatening stimuli or fearful faces activates the central amygdala, which receives inputs from several visual areas (superior colliculi, visual thalamus, and visual association cortex). Patients with damage to primary visual cortex or visual association cortex may have no conscious awareness of looking at a person’s face, yet they may still show amygdala activity in response to viewing faces and often mimic the presented facial reaction (happy or fearful face).  The central nucleus of the amygdala controls many aspects of emotional responses by sending information throughout the brain.  RECOGNITION OF EMOTION: BEYOND THE AMYGDALA Beyond the amygdala, many brain areas are activated when we view emotional faces, including the somatosensory cortex, insular cortex, premotor cortex, and cingulate cortex It seems that all these brain regions, particularly in the right cerebral hemisphere, are involved in recognizing emotions in others. Some people with damage in these regions cannot identify emotional facial expressions in other people. BEYOND THE AMYGDALA  PREFRONTAL CONTROL OF EMOTIONS Role of Ventromedial Prefrontal Cortex (vmPFC): Involved in regulating expressions of emotions; usually has an inhibitory influence. When learned fear responses (e.g., tonefear) are extinguished (tonenow neutral again), connections between the vmPFC and amygdala are strengthening. Lesioning this pathway selectively disrupts extinction learning and restores the original fear memory. People with damage to their vmPFC often struggle to control their emotions. In this respect, they act more childlike. People with a healthy vmPFC can usually calm themselves when they get frustrated and thus suppress emotional outbursts.  VENTROMEDIAL PREFRONTAL CORTEX (ORBITOFRONTAL CORTEX ) Interactions between the PFC and amygdala regulate emotional responses. In the mid 1800’s, Phineas Gage was a victim of a tragic construction accident; an explosion sent a 3 cm thick, 90 cm long tamping rod through his face, skull and brain. Before his injury he was good natured, kind, responsible, well-liked, and respectable. After his injury, he was childish, irresponsible and thoughtless of others. He had severe temper outbursts and used profane language. He was unable to make plans or carry them out. He lost his job and his friends. Reconstruction of the brain Damage to the vmPFC does not strongly affect injury of Phineas Gage cognitive abilities, but it severely weakens behavioral control and impair decision-making. These impairments seem to be a consequence of emotional dysregulation.  RISKY BEHAVIOUR AND IMPULSE CONTROL There is a small correlation between risky behaviour, impulsive aggression, and low serotonin levels. The serotonin metabolite 5-HIAA was measured in the cerebrospinal fluid of rhesus monkeys that were tracked over 4 years. The monkeys with the lowest levels of 5-HIAA were risk takers. They took dangerous unprovoked leaps between trees and were highly aggressive towards older, dominant males. They typically died early from attacks by stronger monkeys. In humans, low cerebrospinal 5-HIAA has been associated with aggression and antisocial behavior, including assault, arson, murder, and child beating. Drugs that increase serotonin signaling, such as SSRIs like Prozac, tend to decrease irritability and aggressiveness.