Emotions Basics & Basic Emotions

Neurotransmitters involved in emotion

  • Norepinephrine: secreted from the locus coeruleus, involved in fight/flight response, arousal, stress, fear

  • Serotonin: mood/impulsivity

  • Dopamine: synthesised in the ventral tegmental area. Involved in motivated behaviour, motion, reward behaviour

  • Synaptic transmition: glutamate (excitatory) and GABA (inhibitatory)

  • Neuromodulators (NE, S, D) Not secreted from one neuron to the other, but exists in the synaptic cleft and makes the postsynaptic neuron more/less susceptible to the action potential from the presynaptic neuron

    • However in some brain areas this changes, eg sometimes dopamine acts in synaptic transmission

Neuromodulators: neuropeptides and steroid hormones

  • Secreted within the brain, starting with the hypothalamus.

  • Hypothalamus sends signals to the pituitary gland, which produces peptides

    • Opioids (endorphins): pleasure and motivation

    • Vasopressin: social aggression

    • Oxytocin: social bonding

  • Steroid hormones: testosterone and cortisol. Slower responses (10/15minutes)

Autonomous nervous system: parasympathetic (rest and digest) and sympathetic (fight or flight) branches. Reptillian brain

  • Parasympathetic: returns the body to a relaxed state when activated. Provides digestion abilities

  • Sympathetic: prepares the body for the stress response. Reduces digestion

  • Behaviour is based on reactivity

Paleomammalian complex: limbic system → more developed hypothalamus which can control the autonomous nervous system

  • Hypothalamus receieves info from the limbic areas. Striatum, amygdala, insula, hippocampus

  • Based on all of these inputs, there can arise more controlled behaviour as they provide context for the situation

  • Also allows for behavioural conditioning and learning by associating emotional experiences to an event

Neomammalian cortex: neo-cortex. Rational stream of info is combined with emotional information. The vmPFC involved in balancing these streams of info

Emotion

  • Emotional reaction: immediate bodily reaction eg surprise

  • Emotional feeling: the subjective experience of the emotion

  • Emotional mood: diffuse affective state, longer term, less intense

Theories of emotion

  • James-Lange theory: an event causes bodily arousal which generates the emotional experience. But the same bodily arousal can cause different emotional experiences (eg raised heart rate)

  • Cannon-Bard theory: reversed the theory - emotion causes bodily arousal.

  • Schachter & Singer: the bodily arousal and emotional experience are parallel systems in the brain but not the same system. They both contribute to the overall emotional experience.

    • Event → (arousal + interpretation) → emotional experience

    • Adrenalin injection experiment: the adrenaline caused arousal in everybody, but those in a happy situation interpreted it as pleasant arousal, those in an angry situation interpreted it as an angry experience

  • However sometimes the James-Lange theory still holds. Without emotional context someone can experience strong emotional reactions (eg PTSD). Raising the questions are there ‘core’ emotions that are biologically based and exist for everybody?

Facial expressions = functional

  • Fearful expression: opens up the eyes to increase visual field size + move the eyes quicker, increased nostril volume and increased air velocity in breathing when fearful → used to detect signal molecules from others?

  • Disgust does the opposite, especially reduces air entry to reduce potential toxic particles

Emotions universality

  • Emotional recognition task across multiple different cultures: sad, happy, disgust, surprised, anger, and fear were consistently recognised universally. They have evolutionary origin.

    • However this research has been criticised because the western labels of emotions were used. The use of these labels pushes what westerners see as the universal emotions

  • Experiment done in a Namibian community (Himba) without using the western labels. Participants asked to sort pictures of emotional responses into 6 categories. 2 categories were consistent across Himba and American samples - happy and fear. All the others were mixed up

    • Conclusion: fear, happiness and disgust are the 3 basic emotions. Disgust did not appear within the basic categories indicating that disgust has mainly a protective function, not the function to signal something to others

    • These 3 emotions are linked to dedicated brain areas

      • Fear: amygdala → avoidance of threat

      • Disgust: insular cortex → avoidance of illness and contamination

      • Happy: striatum → approach of rewards and goals

Basic social emotions

  • Anger: links to social hierarchy, competing with each other. However there is no specific brain network/neural substrate for anger

  • Sadness: links to care for offspring and family. Again no specific neural substrate

  • Can be classified as complex emotions along with guilt, pride, jealousy: strongly culturally influenced, linked to empathy, not biologically based

Amygdala and Fear

Multiple subregions

  • Basolateral: consists of cortical-like tissue. Has grown more in evolution as the percentage of our brain made of cortical-like tissue has increased (subcortex and neocortex). Fear regulation, threat conditioning.

  • Central part: made of striatal-like tissue. Fear expression centre

Visual threat processing → low and high route

  • High route: visual image goes to the visual thalamus, passed to VC, image is seen conciously. It travels to the amygdala and neocortex so that the threat can be assessed

  • Low route: shortcut from visual thalamus to the amugdala. Preconsciously (before the visual image is processed) there can be a threat response generated by the amygdala to allow immediate response

    • Evidence: amygdala reacted stronger to eye-whites of fearful faces compared to happy faces even when they were not consciously processed

Facial fear processing: Urbach-Wiethe disease

  • Amygdala starts to calcify (becomes a bone-like structure) over the course of life

  • UW patients have difficulty recognising fear. When presented with a fearful face, patient SM looked at the nose and not the eyes. She had the ability to recognise fear, but did not have the tendency to analyse the face properly using the eyes

  • South African patients:

    • Showed an increased response to fearful faces compared to healthy controls

    • Only the basolateral amygdala tissue was damaged but the central and medial regions were intact. Reduced ability to learn fear association

    • Central medial is the output of the amygdala, generates bodily responses in response to the fear input. Regulated by the basolateral part

Social reward learning

  • The amygdala facilitates social reward learning, eg a child watching their parents’ reaction when they play with a certain toy

The amygdala provides limbic control over motivational drives → going beyond fear processing

Insula and Disgust

Responds to visual and auditory disgust (in voice), and moral disgust

Involved in taste and pain perception

Monitors bodily perception in general → interoceptive awareness. The influence that the parasympathetic NS or sympathetic NS has on the body is experienced by the insula

Main node of the salience network

Reward and Motivation

Motivation system

  • ‘Reptillian’ regions: ventral tegmental area, substantia nigra

  • Limbic system striatum regions: dorsal and ventral part nucleus accumbens)

  • Cortal regions: OFC, anterior cingulate cortex

Reptilian regions

  • Provide the striatum with dopamine

  • Dopamine acts as a neuromodulator, not a neurotransmitter.Enters the vicinity of the neurons in the striatum

  • Dorsal striatum: expression of motivated behaviour. Habit formation. Motor behaviours associated with getting thr reward

  • Ventral striatum (nucleus accumbens):: experience of reward. activity corresponds with feeling of reward.

    • Reward anticipation and prediction: when the conditioned stimulus is percieved, the NAcc activates as reward is predicted

    • If no reward is given, there is a dip in activation. These neurons firs signal getting the reward, then once they learn the reward is coming they anticipate it

Cortical areas

Orbitalfrontal cortex

  • Computing/predicting whether a stimulus is currently rewarding. Modulates difference between liking and wanting

  • Provides behavioural flexability, behaviour can be adusted based on the current situation.

Anterior cingulate cortex

  • Conflict monitoring, within the self and observed conflict

  • If it is learned that a stimulus will lead to reward but then the reward doesn’t happen, the ACC adjusts behaviour accordingly

  • Dorsal part: cognitive conflict → classic stroop task

  • Ventral part: affective conflict → facial expression stroop task

Emotional Decision Making

Somatic marker theory: a problem/question needs to be interpreted and causes a stream of emotional informational based on previous experience. A decision is made using both the interpretation and emotional experience

  • Theory: it is better to use both emotion and rationality to make decisions

  • Iowa gambling task: 2 high risk/high reward card decks which eventually lose money, 2 low reward decks which eventually gain money

    • Somatic signals (SCR) help us learn which decks are more beneficial, drawing cards induces SCR

    • SCR are higher when cards from the ‘bad’ decks are picked, due to higher losses

    • People with vmPFC damage did not learn to update their behaviour, still drew cards from the bad decks

Morality

  • People with vmPFC damage are more utalitarian

Emotional information is combined with cognitive information (rationality) for decision making in the vmPFC