Emotion 2 Flashcards
Evaluate the evidence that different brain regions are important for emotional processing.
How do cognitive and physiological factors interact in the production and expression of emotions?
Think
Essay plan:
- Define emotion
- Amygdala – review
- Amygdala lesions – SM
- Amygdala – fear: Costafreda et al., 2008
- Hennenlotter et al 2005
- Sharot et al., 2007
- Hippocampus; Part of limbic system Involved in formation of long-term memories, also involved in emotion regulation
- Prefrontal cortex (PFC)
- Activity of neurons when patients view photographs (Kawasakki et al)
- In a PET study of 12 healthy females who watched films that evoked emotion (Reiman et al., 1997) •
- Theories of lateralization: Right hemisphere model:
- Wager et al performed a meta-analysis of 65 studies comparing the lateralisation of emotion. •
- The role of brain in emotion Anatomical components: Wicker et al., 2003.
Emotion
Emotion is, in everyday speech, a person’s state of mind and instinctive responses, but scientific discourse has drifted to other meanings and there is no consensus on a definition. Emotion is often intertwined with mood, temperament, personality, disposition, and motivation. On some theories, cognition is an important aspect of emotion. Those acting primarily on emotion may seem as if they are not thinking, but mental processes are still essential, particularly in the interpretation of events. For example, the realization of danger and subsequent arousal of the nervous system (e.g. rapid heartbeat and breathing, sweating, muscle tension) is integral to the experience of fear. Other theories, however, claim that emotion is separate from and can precede cognition. Emotions are complex. According to some theories, they are a state of feeling that results in physical and psychological changes that influence our behavior. The physiology of emotion is closely linked to arousal of the nervous system with various states and strengths of arousal relating, apparently, to particular emotions. Emotion is also linked to behavioral tendency. Extroverted people are more likely to be social and express their emotions, while introverted people are more likely to be more socially withdrawn and conceal their emotions. Emotion is often the driving force behind motivation, positive or negative. An alternative definition of emotion is a “positive or negative experience that is associated with a particular pattern of physiological activity.” According to other theories, emotions are not causal forces but simply syndromes of components, which might include motivation, feeling, behavior, and physiological changes, but no one of these components is the emotion. Nor is the emotion an entity that causes these components. Brain regions involved in emotion are the amygdala, hippocampus, insula, ACC, hypothalamus, hemispheric differences. Factors in Emotion: Toates (2001) - four basic aspects of emotion: Behavioural, Physiological, Cognitive, Subjective. What we measure: Physiological response, Neuroimaging mostly via: Subjective report of emotions or cognition (rarely evoke behaviour).
Amygdala – review: patients with amygdala damage do not attend to “fearful” faces
The amygdala is thought to play a special role in memory for the emotional significance of experiences and has been discovered to be closely associated with fear and negative emotions. Lesions in amygdala reduce fear response, patients with amygdala damage do not attend to “fearful” faces. Amygdala may direct attention to salient features and therefore may be important in emotions other than fear. For instance, the impaired recognition of facial expressions of fear in a patient with amygdala lesions (Adolphs et al. 1994) was found to result from an inability to guide one’s gaze and visual attention to features in faces normally salient to recognize such expressions, notably the eye region of the face. Another study found that sequences of unpredictable tones elicited greater amygdala activation, compared with predictable tones, even when no overt rewarding or punishing outcomes were associated with those tones (Herry et al. 2007). These recent findings support earlier ideas that the amygdala is involved in vigilance for stimuli (in all sensory modalities) that are potentially salient because they are ambiguous or unpredictable. Amygdala may direct attention to salient features (Adolphs, 2009). If this is correct, amygdala may be important for emotions other than fear.
Amygdala – review: fear vs neutral: Costafreda et al., 2008
Costafreda et al. (2008) reported quantitative estimates of the selectivity of amygdala for different emotions relative to neutral material. For example, they found that the amygdala is four to seven times more likely to be activated by fear than by stimuli of neutral content. This probabilistic estimate may be useful in the interpretation of a particular study finding by quantifying the specificity of the link between an area (or network) and a cognitive process. This estimate also acts as an explicit reminder of the limitations in reverse inference, in that such link is not absolute, but probabilistic and necessarily relative to an alternative state (in this example, a neutral stimulus). Therefore, detecting amygdala activation in a particular experiment cannot lead to the conclusion that the task must have involved a fearful stimulus, but simply that it is more likely that the stimulus was fearful than neutral. Additionally, this single estimate cannot exclude a number of credible alternatives, such as amygdala reactivity to social stimuli per se or emotions other than fear.
Positive emotions associated with the amygdala, Hennenlotter et al 2005
There is accumulating evidence suggesting that the visual representation of facial affect is closely linked to its motor representation. To examine whether perception of pleasant facial affect involves neural circuitries associated with its production, we performed an fMRI experiment with ‘compressed image acquisition’ where subjects smiled and observed movies depicting other people smiling within scan-free time intervals between the acquisition of each image volume. Overlaps between the brain activation during observation and execution of smile expressions were located in the right premotor cortex and pars opercularis of the inferior frontal gyrus, right parietal operculum (SII) and left anterior insula. Observation of smile expressions further yielded signal increases within the posterior superior temporal sulcus (STS), fusiform gyrus and ventral amygdala. The results show that perceiving and expressing pleasant facial affect share a common neural basis in areas concerned with motor as well as somato- and limbic-sensory processing.
In concert with temporal regions serving the visual analysis of facial expressive features, a mapping of the observed expressions onto neural circuitries associated with the production of these expressions and its somatosensory consequences could provide a description of what the expression would feel like if produced in the observer. Such a mechanism is suggested to be important for empathic understanding of others’ feelings. But amygdala also implicated in positive emotions. Ventral amygdala activated by positive facial expressions (smile) in others as well as inferior frontal gyrus, anterior insula, superior temporal sulcus & fusiform gyrus. But ventral amygdala (superior temporal sulcus & fusiform gyrus) are not activated when smiling oneself. Amygdala has many input & output connections to cortex and subcortical regions; inc input from olfactory bulb (pheremones). Right-handed young adults; happiness ratings viewed positive, negative and neutral pictures and rated whether pictures made them feel positive or negative. Activation in both left & right amygdala correlated with positive feelings yet there was no correlation with negative feelings. During stimulation of amygdala, negative or positive emotions reported depending on which nuclei stimulated. Information from other brain regions is brought together in the amygdala where emotional significance may be added. Amygdala by be a sensory gateway for emotion, as part of a network. Sensory information takes 2 routes from thalamus to amygdala, short or long. Short route: direct, fast. Long route: via cortex, slow. Short route may enable fast response/reaction to stimuli. Long route via cortex may enable amplification or inhibition of emotion through cognition.
Hippocampus; Part of limbic system Involved in formation of long-term memories, also involved in emotion regulation: Kensinger & Corkin, 2004.
Study of 28 students fMRI scan while encoding & retrieving words that were neutral, negative and nonarousing (e.g., sorrow, mourning, etc.), or negative and arousing (e.g., rape, slaughter, etc.). At encoding, left amygdala, hippocampal & inferior parietal lobule activation was greater for negative than neutral words. Looking at brain activity at encoding to explain later memory performance (at retrieval) Left hippocampal activation was greater for later-remembered versus later-forgotten words. Left amygdala activity was greater only for later remembered arousing words Correlation between activity in amygdala & hippocampus.
Prior investigations have demonstrated that emotional information is often better remembered than neutral information, but they have not directly contrasted effects attributable to valence and those attributable to arousal. By using functional MRI and behavioral studies, we found that distinct cognitive and neural processes contribute to emotional memory enhancement for arousing information versus valenced, nonarousing information. The former depended on an amygdalar-hippocampal network, whereas the latter was supported by a prefrontal cortex-hippocampal network implicated in controlled encoding processes. A behavioral companion study, with a divided-attention paradigm, confirmed that memory enhancement for valenced, nonarousing words relied on controlled encoding processes: concurrent task performance reduced the enhancement effect. Enhancement for arousing words occurred automatically, even when encoding resources were diverted to the secondary task.
Prefrontal cortex (PFC):
The medial potions of the pre-frontal lobes (including the medial portions of the orbital cortex and the cingulate cortex) are the sites of emotion-cognition interaction that have received the most attention. Functional brain imaging studies have found evidence of activity in the medial prefrontal lobes when emotion reactions are being supressed or re-evaluated. In studies under that use suppression paradigms, participants are directed to inhibit their emotional reactions to unpleasant films or pictures: in studies using the reappraisal paradigms, participants are instructed to reinterpret a picture to change their emotional reaction to it. The medial prefrontal lobes are active and seem to exert cognitive control of emotion by interacting with the amygdala.
Activity of neurons when patients view photographs (Kawasakki et al)
Microelectrodes were used to record 267 neurons in the anterior cingulate cortices of four patients prior to surgery. They assessed the activity of the neurons when the patients viewed photographs with emotional content. Of these 267 neurons, 56 responded most strongly and consistently to negative content. Supporting previous research that linking the medial prefrontal lobes with negative emotional reactions, but also shows that not all neurons in the same area perform the same function- neurons directly involved in emotional processing appear to be sparse and widely distributed in the human brain.
In a PET study of 12 healthy females who watched films that evoked emotion (Reiman et al., 1997)
In a PET study of 12 healthy females who watched films that evoked emotion: happiness, sadness or disgust. Emotional films lead to increased activity in medial Pre-Frontal Cortez, thalamus, hypothalamus, amygdala, anterior temporal cortex. No difference in type of stimuli, may reflect evaluation of emotional stimuli.
Lateralization of emotion:
Emotional lateralization is the asymmetrical representation of emotional control and processing in the brain. There is evidence for the lateralization of other brain functions as well. A variety of scientific studies have found lateralization of emotions. FMRI and lesion studies have shown asymmetrical activation of brain regions while thinking of emotions, responding to extreme emotional stimuli, and viewing emotional situations. Processing and production of facial expressions also appear to be asymmetric in nature. Many theories of lateralization have been proposed and some of those specific to emotions. Also, some of the evidence is contradictory. Many brain regions are interconnected and the input and output of any given region may come from and go to many different regions.
Theories of lateralization: Right hemisphere model:
The right hemisphere has more control over emotion than left hemisphere. The right hemisphere is dominant in emotional expression in a similar way that the left hemisphere is dominant in language. The right hemisphere is dominant in the perception of facial expression, body posture, and prosody. The right hemisphere is important for processing primary emotions such as fear while the left hemisphere is important for processing social emotions. General lesions in the right hemisphere reduce or eliminate electrodermal response (skin conductance response ((SCR)) to emotionally meaningful stimuli while the lesions in the left hemisphere do not show changes in SCR response.
Subject SB-2046 had part of his right, prefrontal lobe removed because of cancer. While his IQ and a majority of other normal functions were unharmed, he had severely impaired decision-making skills especially when he had to consider immediate vs. future reward and punishment. His decisions were almost always guided by immediate reward or punishment and disregarded any long-term consequences. Researchers were incapable of conditioning patient SB-2046 to nonverbal stimuli containing emotional meaning (reward or punishment), but were able to condition the patient to verbal stimuli containing emotional meaning.
Wager et al performed a meta-analysis of 65 studies comparing the lateralisation of emotion.
The MAIN conclusion was current theories of lateralisation of emotion are too general from a neuroanatomical perspective, overhaul comparison between the left and right hemisphere reveal no interhemishpheric differences in either the amount of processing or the valence of emotions being processed. However when the comparisons were conducted on a structure by structure basis, they revealed substantial evidence of lateralisation of emotional processing. Functional brain imaging studies have commonly observed lateralisation in the amygdale- more activity is often observed in the left amygdala.
The role of brain in emotion (disgust) Anatomical components: Wicker et al., 2003.
We performed an fMRI study in which participants inhaled odorants producing a strong feeling of disgust. The same participants observed video clips showing the emotional facial expression of disgust. Observing such faces and feeling disgust activated the same sites in the anterior insula and to a lesser extent in the anterior cingulate cortex. Thus, as observing hand actions activates the observer’s motor representation of that action, observing an emotion activates the neural representation of that emotion. The anterior insula was activated in both self (odour) and other (visual) - disgust conditions.
Insula / Insular cortex between the frontal and temporal lobes, Extensive connections to limbic system including amygdala, PFC, ACC (Anterior Cingulate Cortex). Insular activity correlates with perception of internal bodily states, ie thirst, touch, heartbeat and also involved in pain perception. Insula involved in disgust and nausea, as well as complex emotions such as guilt. Insula activated in response to joy & disgust and seeing these in others often activates with Anterior Cingulate Cortex (ACC). Both Insula & ACC may be involved in identifying others emotions.
Summary
Our subjective experience of emotions seems to be based upon an interplay between physiological (i.e., autonomic) reactions and the cognitive appraisal of our context. This is mediated by complex neurological systems – acting as a network and including neurochemical changes in brain. Emotional research: Some researchers have suggested that: –we should only study emotions that can be mapped in animals (“survival circuits”) –we should avoid the subjective experience in favour of physiological or neurological measures. Different methods employ different experimental stimuli but, fundamental part of human experience so warrants research.
