Emotions.pdf

Emotions - system for evaluating options and actions - Basic systems for assessing danger and reward - Evaluating choices - Related to goals, action, other people REGIONS: - Amygdala Hippocampus mamillary body Fornix Anterior/posterior cingulate cortex Septal area HYPOTHALAMUS Links brain and bo...

Emotions - system for evaluating options and actions - Basic systems for assessing danger and reward - Evaluating choices - Related to goals, action, other people REGIONS: - Amygdala Hippocampus mamillary body Fornix Anterior/posterior cingulate cortex Septal area HYPOTHALAMUS Links brain and body responses to emotion - relay center - Homeostasis - HPA AXIS: STRESS RESPONSES - Hypothalamus, pituitary gland, adrenal gland - Changes in cognitive function are very likely to a ect emotion processing HYPOTHALAMUS INFLUENCES AUTONOMIC RESPONSES ff fl Sympathetic response: - Dilates pupil, increases heart rate and respiration, raises blood pressure, greater perspiration - Fight and ight responses Parasympathetic response: - Contracts pupil, decreases heart rate and respiration, reduces blood pressure and perspiration - Relaxation and a liative responses HPA AXIS - Hypothalamus releases hormone (releasing factor) that stimulates the pituitary gland - Pituitary secretes hormones which stimulate the adrenal gland - Adrenal produces stress-related hormones including adrenaline and cortisol - Short-term production of stress hormones helps prepare the body for emotion/reward driven responses - Long-term production of these hormones can shape overall brain and behavioural responses • Linked to poorer health and mental health outcomes • Can change equilibrium • Can change behavioural responses AMYGDALA AND FEAR-BASED LEARNING REGIONS: - Basolateral nuclei: • Hippocampus - link to memories (a ective) to gauge whether we want to repeat or avoid • Frontal cortex • Nucleus accumbens (reward) - Central and corticomedial nuclei: • To hypothalamus • Modulating autonomic “ ght/ ight” system • Modulating HPA axis • Global stress - central nucleus: • Global planning associated with reward/or not • High level emotional processing DISSOCIATION OF FEAR LEARNING AND DECLARATIVE MEMORY - Amygdala lesion impairs fear learning, but not memory - Hippocampus lesion impairs memory, but not fear learning - Amygdala + hippocampus lesion impairs both Fear conditioning + Skin Conductance Response + Declarative memory - Conditioning responses to di erent stimuli • Some fruits paired with shock = response in skin conductance (sweaty ngers = salt = fi ff fl fi ff fi ffi electrical conductance) • Looking at SCR • Then asked speci c questions - “ Did you see an apple/orange?” - Controls: CS (orange paired with shock) = strong SCR for CS vs UCS + good at remembering - Amygdala damage: no change in SCR for CS (no learning of association between US+shock), emotional valence that learns about stimuli is impaired + good at remembering - Hippocampal damage: CS = strong SCR for CS vs UCS + bad at remembering - Amygdala + hippocapal damage: no change in SCR for CS (no learning of association between US+shock), emotional valence that learns about stimuli is impaired + bad at remembering Why is it relevant?: Surgeries for epilepsy remove: - Amygalda - Susceptible for epilepsy - Hippocampus - Generate/propagate bad electrical signal (epilepsy) - Amygdala + hippocampus - If epilepsy is very severe NOT JUST FEAR LEARNING/NEGATIVE STIMULI Face memory task - Right dLPFC more active for all remembered faces compared to forgotten faces - Greater dLPFC and amygdala activity for fearful and happy compared to neutral • More regions than amygdala important for emotional responses • Not just for bad stimuli since activity for happy faces as well Meta-analysis of emotional stimuli - Does it matter if negative or positive stimuli? - Is right or left amygdala more important - Evidence that suggests that right is important for processing emotional stimuli - Conclusion: - showed activity in left and right amygdala for positive and negative stimuli, especially faces - Evolution: looking at the face is important to gauge whether to approach or avoid AMYGDALA: FAST AND SLOW - Fast route: sensory → thalamus → amygdala • Automatic reactions to known stimuli - Slow route: sensory → thalamus → cortex → amygdala • All levels of cortex have access to the amygdala (language, face and object areas) • Learning of emotional valence of novel stimuli • Underlies memory enhancement e ect: emotionally charged events/stimuli are better remembered REWARD PROCESS ff - Dorsal striatum • Caudate & putamen: connected to dLPFC and ACC - Part of basal ganglia connected to frontal cortex Reward valuation in the context of action • - Ventral striatum • NAc: connected to mPFC and hippocampus • Reward valuation of objects, events - Common activity in reward areas for money, food, and sex • Both dorsal and ventral striatum - food rewards: ACC and vmPFC & OFC - Monetary rewards: - Erotic rewards: MUSIC AND REWARD - Consistent striatal responses to highly pleasurable music - Using PET (O15, Raclopride, BOLD) - Subject had to choose a song they preferred - Linked to activity in dStr & changes in BOLD signals - Music Purchasing (“iTunes”) Paradigm • Subjects had preferred genre • Activity in NAc scaled with the amount of money paid - Increased liking = increased willingness to pay = more activity • Activity in rNAc correlated with auditory cortex - Enhanced the more you liked/willingness to pay - Similar for NAc to vmPFC • Response/evaluation of more complex stimuli (i.e. music) = interaction with cortical areas and frontal regions - Not just amygdala - Reward Structures enhance their Functional Connectivity with Cortical Systems as Value Increases ANTERIOR CINGULATE : ACTION AND REWARD - ACC is part of the limbic system, a set of connected structures linked to emotion processing • Connected to amygdala and frontal lobe - Di erent regions engaged in speci c processes related to their connections • signi cant overlap - Selecting actions based on e ort and motivation • squeeze for apples study= activity in ACC - Involved in selecting actions when the outcome is fi ff fi fl ff uncertain • con ict monitoring EMOTION AND DECISION MAKING - Orbital frontal cortex (OFC), ventromedial frontal cortex (vmFC) • Connected to ventral striatum/NAc • Also connected to amygdala and hippocampus - Primary role in evaluation of rewards to guide behaviour - vmFC engaged by primary rewards along with ventral striatum - OFC engaged in valuation of music to be purchased IMPAIRED DECISION MAKING - Damage to OFC and/or vmFC causes: • Changes in behaviour despite in tact cognitive function: - socially inappropriate comments, gambling and risk taking, theft, risk-taking - Think of the cases of Phineas Gage and James Brady • De cits in judgement and decision making - Associated with psychopathy • Speci c de cit in assessing costs/bene ts of actions and outcomes - Di culty switching behaviour in response to feedback - Think of frontal lobe de cits for Wisconsin Card Sorting IOWA GAMBLING TASK - People given 50 trials to win as much money as possible • Max reward di ers between “good” and “bad” decks • Decks A and C have 5 small losses and 5 gains • Decks B & D have 9 gains and 1 large loss - controls: get better and better as they learn - People with orbital frontal damage do poorly - People with substance dependence do poorly OFC AND REGRET - Big di erence when loss compared to expectation - Greater activity in OFC when people lost more and thus regretted their choices RATS AND REGRET - Di erent avours were associated with di erent waiting times on each trial • Animals had to decide to wait or switch - Activity in OFC and NAc was greater when they got their treat/preferred reward • But, activity also related to their previous choice when they switched and the wait time for ff fi fi ff fi fl ff fi fi ffi ff the new option was longer/reward was not their preferred choice - Regret - Responses in brain regions similar to humans ASYMMETRY AND EMOTION - Right hemisphere damage impairs recognition (parietal lobe) and memory (temporal lobe) for faces • Left visual eld is more emotionally salient • Because of specialization of left hemisphere for language & simultaneously right hemisphere specialized for emotions and music PERCEIVING EMOTIONAL EXPRESSIONS - Right hemisphere damage impairs recognition (parietal lobe) and memory (temporal lobe) for faces - Right amygdala damage impairs recognition of emotions in faces - People with right amygdala damage do not look at the eyes and mouth: most relevant features for decoding emotion - Cause or consequence? - Amygdala particularly sensitive to features of the eyes and mouth that are associated with emotional expressions PRODUCING EMOTIONAL EXPRESSIONS - Mirrored left halves appear more emotionally expressive - People with right hemisphere lesions are rated as less emotionally expressive when they speak - Video analysis shows that emotional expressions start with the left side of the face LEFT IS BEST - Because the left visual eld (represented in the right hemisphere) is more sensitive to fi fi emotion, talkers who want to express emotion turn to the right, showing the left side of their face – which is controlled by their right hemisphere