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Lecture 9

Lecture 9 notes- WORD FOR WORD what the prof says!

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University of Toronto Scarborough
Rutsuko Ito

NROC61 – Lecture 9 – The Limbic System and Emotion IGNORE FIGURES IN THE TEXTBOOK!!! ONLY NEED TO KNOW FIGURES FROM THE LECTURE SLIDES!!! We will talk about the different models of emotion being proposed. Emotions – what would the world be without them? - William James 1890 - “ If you can conceive of yourself… suddenly stripped of all the emotion with which our world now inspired you… no one portion of the universe would then have importance beyond another; and the whole character of its things and series of its events would be without significance, character, expression, or perspective.” - William James 1890 said that living without emotion would be boring. Imagine a world without emotion, not being able to feel anything, or respond to anything, etc would be uninteresting. Definition of Emotion - Emotions are biologically-based responses to situations that are seen as personally relevant. They are shaped by learning, and usually involve: o Changes in peripheral physiology o Expressive behaviour o Subjective experience - In order to get a definition of emotion there will be several components involved for it to be an emotional experience. Emotion is very much rooted in biological response and is personally relevant. It is shaped by learning and there are three components that are important, - 1. Emotion is expressed as changes in peripheral physiology, - 2. It is also expressed in behavior (emotions cause us to do something, they don't just arise and have no consequences. They usually do have consequences which lead us to emit some sort of behavior in response. For example, responding to an emergency event is an action that is induced by emotion.) - 3. There is also a subjective element to it. We have all experienced emotion that is a subjective experience. We don't know whether animals actually experience emotion in similar ways. This is the problem with animal models since subjective experience or the ability report some sort of subjective experience is lacking in animal models. Dimensions of Emotion - We have different dimensions of emotion in terms of valence. Some emotions can be positive (for example, happy) while other emotions are very negative. You also have to think about the intensity of those emotions. Some emotions are accompanied by very high states of arousal and others are accompanied by low states of arousal. So you can place emotions into the different quadrants of dimensions. Emotional Expressions - If we were to focus first on the expression of emotion, such as physiological expressions, there may be something like blushing where there is increased blood flow and vasodilation for a high arousal phase. Many of these are autonomic responses. Your respiratory system also can be affected as the respiratory rate goes up and body temperature changes. The autonomic response in fear conditioning in humans is measured through skin conductance. There are also motor expressions of behavior such as facial expression. We interpret emotions in others by their tone of voice, gestures, posture, and their own self-reports. Humans are able to report how they feel and what they feel at the same time. - Physiology o Changes in heart rate, blood pressure, breathing rate o Changes in muscle tension o Changes in perspiration (skin conductance response, SCR) o Changes in perceived body temperature o Changes in Sensory sensitivity (eg. Pain) - Distinctive Motor Behaviour o Facial expression, tone of voice, posture - Self-Reported Cognition Emotional Expressions - The dominant thought in the late 1800s during Darwins time was that humans have the ability to process and express emotion. Darwin conducted a detailed analysis of physiological responses of two different emotions in animals. He concluded that whether the person is young and old, from different races, or man or animal, they all express the same state of mind by the same movements. His conclusion was that all races, all humans, and animals all express emotion in a very similar way. So you can see things like hair-raising, vocal emissions, perspiration, and facial muscle movements are all expressed whether animal or human beings. - Darwin’s “ Expression of the Emotions in Man and Animals” (1872) – “the young and the old of widely different races, both with man and animals, express the same state of mind by the same movements.’ - Hair raising, vocal emissions, perspiration, facial muscle movements, etc. Emotional Expressions - Examples of facial expressions that people have studied. You can see that monkeys also express similar emotions and facial expressions. What you can conclude is that maybe in higher order animals we have similar facial expressions and similar responses to emotions. Emotional Expression - Ekman: 6 basic facial expressions – fear, happy, surprise, sad, angry, and disgust - Ekman conducted a very systematic study on facial expressions and identified six basic facial expressions in humans: happy, sad, angry, surprise, disgust, and fear. - Models of Emotion What is the link between subjective experience of emotion and the physiological responses to emotion? - The models of emotion that have been composed generally try to link the subjective experience of emotion with the physiological response of emotion. This is what models of emotions try to achieve. Thinking with common sense, if we are exposed to a fearful stimulus, the first thing you think is that you probably experienced it subjectively where you feel fear. Then you might notice that you have a body response or physiological response to that stimulus. Then you might reason to yourself that your heart is because you are fearful. Common sense would dictate that when you are actually exposed to a stimulus, you are aware of your subjective feelings about your emotion first and then you notice that your heart is reacting. James-Lange Theory (1890’s) - The James Lange theory suggests the opposite. If you were exposed to a fearful stimulus, the first thing that happens is the physiological response to the fearful stimulus, followed by the subjective experience or acknowledgment of the fearful subjective experience. You might report that you feel afraid because your heart is pounding. So you are interpreting your own physiological reaction as a subjective feeling. Peripheral body responses influencing emotions - Evidence for the James Lange theory. If you were to hold a pencil tightly between your teeth to force a smile OR if you were to put a pencil between your lips to prevent smiling during a funny movie, research shows that if you were in the smile group, you're more likely to enjoy the movie! Your enjoyment of the movie increases if your mouth is in a smiling position. - Try holding a pencil tightly between teeth (forces smiling expression) or between lips (prevents smiling) during a funny movie – research has found that smiling expression leads to more enjoyment of the movie! Facial Feedback Signal Affecting Emotion - This was done in a more tightly controlled experiment. They had 96 female undergraduate students who were assigned to four groups. The difference between C and D was that that Duchenne muscles (which are facial muscles that constrict when you smile) if they are involved in smiling will this make a difference or not as opposed to a non-muscle smiling. While these four groups of students held their facial expressions in the certain ways, they were presented with different stimuli of silent video clips to induce different emotions. Autonomic measures were also taken. They were not told what the nature of the experiment was. - Soussignan 2002 - 96 female undergraduates - Randomly assigned to 4 group: o A. Control o B. Lips pressing o C. Non-Duchenne Smiling o D. Duchenne (full facial) smiling - Stimulus: 8 x 10sec silent video clips (eg: landscapes, animals, funny cartoons, mutilated body) to induce different effects. - Autonomic measures: heart rate, temperature, skin conductance - Subjects were not given cover story so as not to guess the nature of the experiment. - Peripheral Body Responses Influencing Emotions - They found that the Duchenne smiling the group as a whole reacted more positively to the clips that were shown compared to any other group. The clips are more neutral than positive or negative. The idea is that if you were to peripherally force yourself to smile, you are more likely to interpret a subjective experience associated by smiling as being pleasant. Therefore peripheral body responses actually enhances emotions in these studies. - The Duchenne smiling group on the whole reacted more positively to the video clips compared with other groups. - Critism of James –Lange Theory - There is evidence for The James Lange theory however there is also criticism. For example if you were to conduct a spinal cord transection and cut off the spinal cord from the brain, it has been proven that experimental animals and humans still experience emotion. So they don't need peripheral feedback or body feedback to feel emotion. You don't need peripheral responses in order to feel something. Also what you get with visceral reaction or autonomic reaction are quite similar across different arousal situations such as aerobic exercise or feeling danger. The body reactions are common to many different types of subjective experiences. Sometimes you could argue that the autonomic nervous system response is just too slow to be the source of split-second decisions that you make about your emotional state. - Experimental animals and human patients continue to react emotionally after spinal cord transaction - Visceral reaction is similar across different physiological arousal situations eg: aerobic exercise, feeling danger. - Autonomic nervous system response too slow to be the source of split second elicited emotions. Cannon-Bard theory (1920’s) - A better way of thinking about it may be the Cannon-Bard theory of emotion. The Cannon Bard theory of emotion proposes that the body response and subjective experience happen simultaneously. It isn't that one will lead to the other they have been simultaneously or together. In this way, we can get to our subjective experience first and then have a physiological response after because that might affect us a little bit later or it could be the other way around (awareness of subjective experience can be inhibited or suppressed by cognitive process?). - Cannon-Bard Theory - This theory was quite influential since they were one of the first theories to suggest that they were there was central neural processes involved in emotion. They focused particularly on the thalamus and the hypothalamus as being the driving center of emotion and emotional experience and responses. The thalamus receives sensory input from peripheral sensory organs. It has a very intimate connection of cerebral cortex and the autonomic nervous system as an output. It seemed to be an ideal candidate for sub serving emotional responses. It became more popular than the James Lange theory since it was more plausible. It also suggested that the brain was primarily involved in regulating emotion. More modern theories which suggest that the driving center of emotion it's not necessarily the thalamus or hypothalamus, it is now thought to be the amygdala. - Theory of central neural processes o Focus on thalamus as the driving center for emotional experience and responses:  Sensory information relayed to the thalamus in turn activates the cerebral cortex and autonomic nervous system simultaneously to induce the subjective experience of emotion, and physiological responses. - Considered more feasible and logical than James-Lange theory - However, we will see later that the focus has moved away from the thalamus, and more onto the amygdala as being the center of emotional processing. But Considering Further Evidence - Let’s consider the involvement of cognition in emotion. Schachter and Singer in 1962 came up with an ingenious experiment. They used 184 male undergrad students who were told they were going to be injected with a vitamin substance (suproxin- made up) which was supposed to improve visual skills. In actuality, some of the group were injected with adrenaline which increases heart rate, high arousal. There were 4 groups. The adrenaline ignorant group were not told that they would receive adrenaline and were not told about the side effects of the drug. The adrenaline informed group were given adrenaline and were told of the side effects. The adrenaline misinformed group were given adrenaline but were given false side effects (numb feet, etc.). The Control or placebo group was given saline injection (no adrenaline). NONE of them knew they were being given adrenaline… they were told that they were testing out a new drug. - Schachter & Singer, 1962 - 184 male undergraduates in intro psych asked to participate in a study looking at the effect of vitamin injections (suproxin-made up name) on visual skills. - 4 treatment groups: participants were actually injected with adrenaline, or saline! - The participants were divided into 2 groups: They used actors to induce some type of emotion. In one group they used an actor to perform a number of silly acts to amuse the participant (EUPHORIA CONDITION) and the second group, the actor performed a number of acts to annoy or anger the participant (ANGER CONDITION). Then the participants were all asked to give emotional ratings out of the time they had with the actors. If you looks at the reaction of the different groups, it may not initially make sense but what you can see is that the least happy or least angry group were the ones that were given adrenaline and INFORMED of the side effects. They were the least affected by the performance of the actors. The ones that were angriest were the adrenaline ignorant group. The ones that were happiest were the adrenaline misinformed group who were told the opposite of the side effects of that which they experienced. - Participants were then allocated to 2 emotion-eliciting groups; o 1. Euphoria condition: a stooge performed a number of silly acts designed to entertain and amuse participant. o 2. Anger condition: a stooge carried out tasks and made comments designed to annoy the participant. - Then asked to give emotional ratings after spending time with the actors. - How did the different groups respond? - What’s going on? - The group that was adrenaline misinformed and the adrenaline ignorant responded similarly however the misinformed group was told they were going to feel the opposite of what they actually felt which was high arousal (in terms of being happy). They were most susceptible in the happy condition. - The groups who had no explanations for why their bodies felt the way they did were the most susceptible to the actors. o Why? If a person experiences a state of arousal for which they have no immediate explanation, they will describe their emotions in terms of the cognitions available to them at the time. o They will attribute their emotions to the actors performance because they have no other explanation for the way they feel - Subjects in the adrenalin informed groups (who were expecting certain reactions as a result of the drug administration) gave the lowest ratings in both conditions. o Why? If a person experiences a state of arousal for which they have an appropriate explanation (e.g. ‘I feel this way because I have just received an injection of suproxin (adrenalin)’), then they will be unlikely to describe their emotions in terms of the alternative cognitions available. o They knew that they could attribute their responses to the drug so they would be unlikely to attribute their emotional responses in terms of an alternative cognition available which is the actors performance. - This shows that the presence of physiological responses are not sufficient to drive emotions, but the attribution of emotion is a COGNITIVE act. Cognition of attributing a certain emotion to how you feel is a very important part of recognizing emotions. That is what this experiment shows. - KNOW THAT THE ADRENALIN INFORMED GROUP WAS THE LEAST HAPPY AND THE LEAST ANGRY GROUP. Schachter & Singer’s Two-factor Theory - If we experience some sort of physiological arousal, we are always looking for some sort of explanation or interpretation for our feelings. It is very important that we attribute an emotion to the physiological response or feeling. The idea of cognition involvement in understanding emotion became very important in this theory. - Emotion arises from a combination of a state of arousal and cognition that makes best sense of the situation the person is in. - If we experience physiological arousal, we look for cues to find an explanation for our feelings. - Sometimes, emotions can be misattributed! Creaky Bridge Experiment - Examples in which emotions can be misattributed. - Creaky bridge experiment – 2 groups of all male participants. One group had to cross the very fear arousing wobbly Capilano suspension bridge in BC. This is a very fear arousing situation. The second group had to cross a very stable low, broad bridge. - At the end of the bridge, there was an attractive female who required them to complete a questionnaire based on a particular picture however, that was not the point of the experiment. The point was that the female confederate would basically give the man her phone number in case they wanted to chat further. Interestingly, the men who made to cross over the Capilano bridge made MORE post-interview calls to the attractive female than did the confederate. - The point of the experiment is that they weren’t actually really attracted to the female but they are misattributing their arousal as attraction to the female. - This is a quite specific effect with more attractive females. Further research was done were they found that if person is unattractive, that person is likely to become MORE unattractive after an arousing event. - Dutton & Aron 1974 - 85 males participants; 2 experimental groups: o 1. Those crossing the (fear-arousing) wobbly Capilano suspension bridge hanging 200ft over jagged boulders and rapids. o Those crossing a more stable, low, broad bridge. - An attractive female confederate asks the men to complete questionnaires on the bridge requiring them to write a brief story based on a picture, and also gives them her phone number in case they wanted to ‘talk further’. - Significantly more post-interview calls came from men who had crossed the dangerous bridge! - Dangerous bridge produces high arousal (increased adrenaline) which gets (mis)interpreted as attraction! Two Factor Theory - The two factor theory incorporates the idea that we need cognition in order to be able to process our emotions. So now with cognitive interpretation included in the picture, you could perceive a fearful stimulus as being fearful because you INTERPRET the situation as being dangerous. So cognitive interpretation also comes into play. Modern Take - What about modern theories? Now we think that there are reciprocal connections between these three big factors: Interpretation, physiological response, and fear. Contextual interpretation is a big one in order for us to understand our subjective experience. - The only thing with Schachter and Singer’s interpretation was that it suggested that physiological arousal only influences the intensity of emotion without distinguishing between emotions. This is actually a big thing. A lot of emotions are accompanied or are associated with very similar physiological reactions. How can we actually differentiate between different emotions that we feel. This is an interesting area of research. There are some ambiguous emotions were we find it difficult to interpret between physiological reactions (eg: sad and fear are very different but is it because of the intensity that it is different or do you feel just as intense when you are sad as when you are fearful.  Ambiguous). - Reciprocal connections between all three factors Neural Basis of Emotion Can we map emotion onto certain brain areas? Papez Circuit - Looking at the beginning of neural basis of emotion research. Papez termed the “Papez Circuit” which involves all the regions of the brain listed below. In 1949, Maclean added to the Papez Circuit. They suggested that all these regions are in some way involved in emotional processing. - Papez (1937) o Termed “Papez Circuit” by Maclean (1949) - Mammillary bodies/hypothalamus (expression of emotion) - Anterior thalamic nucleus (also expression of emotion) o Lesions lead to spontaneous crying/laughing - Cingulate gyrus (experience of emotion) - Hippocampus (organizes programs of emotional expression) o Vulnerable to rabies infection – hyperemotional responses (as a result of rabies infection you get hyperemotional responses). Limbic System as Circuit of Emotion - In 1952, Maclean modified the Papez Circuit and included the Amygdala, Orbitofrontal Cortex, and Parts of the Basal Ganglia and called it the “Limbic system”. The limbic system has the hippocampus at its core and the amygdala as a very important part of it. Now, the focus has moved away from the hippocampus as the main area of emotion to the amygdala. The hippocampus is more involved in declarative memory and spatial processes. In terms of the circuit of emotion, now we focus a lot more on the amygdala or the obitofrontal and cingulated cortex as being primary key structures. - Maclean (1952) o Modified Circuit of Papez o Included  Amygdala  Orbitofrontal cortex  Parts of Basal Ganglia - Coined phrase o “Limbic system” –focal point was the hippocampus and its connection with the hypothalamus. - But the focus has now shifted away from the hippocampus as it became known for other processes (spatial processes). - Much more focus on amygdala, orbitofrontal cortex, cingulated cortex Limbic System as Circuits of Emotion - There have been a lot of theories suggesting that there is a single emotional system being the Limbic System. Now it is becoming increasingly clear that maybe some forms of emotion can be mediated by the limbic system but there are also other factors that cannot be just explained in terms of the function of the limbic circuit. There is a consensus on the fact that there really isn’t a one-to-one correspondence between structure and function (so you can’t say amygdala = fear, perhaps you can say amygdala is involved in fear). The processing of emotion is more of a distributed process across different brain areas perhaps within the limbic system, BUT we can’t say that the Limbic system is invariantly involved in ALL forms of emotion. - Difficulties with the single emotion system concept o Diverse emotions o Many structures involved in emotion  No one-to-one relationship between structure and function o Limbic system: Utility of single, discrete emotion system questionable The Amygdala - Nevertheless, it is very important to look at the amygdala since it is the structure most associated with emotion. It sits in the lower midbrain area. - The most critical structure in the brain’s emotional system. The Monkey Amygdala - Kluver-Bucy Syndrome in monkeys has been very influential in terms of identifying the amygdala as being very important in emotion. It is very important to realize that Kluver-Bucy syndrome is NOT induced by selective amygdala lesions it involves bilateral anterior temporal lobe lesions which also includes other structures such as the hippocampus and other areas of the brain. What they found was that there were all sorts of symptoms associated with the syndrome such as loss of fear, disruption of social hierarchy, indiscriminate dietary behaviour, visual agnosia, and tendency to examine all objects orally. - Some of these symptoms are now not known to be the results of amygdala lesions (such as visual agnosia and some motivational deficits). If we were to do selective amygdala damage, we wouldn
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