the emotional brain

neuropsychologists identify emotion as affect, a conscious subjective feeling about a stimilus 

four principal behavioural components to emotion;

• physiology 
• cogniton - self report 
• distictive motor 
• unconscious behaviour 

abstract constructs are diffiuclt to measure - it is an internal state rather than an over behaviour, extremely subjective 

but associated with behaiours and physicologyival reponses that we can observe/measure;

• need to look for clear physiological and/or behavioural correlates of distinct emotions - e.g., fear, anger, happiness 
• can then attempt to discover the underlying neural substrates 

complex emotions e.g., pride and guilt, are harder to observe/measure and thuse prove less amenable to neuroscientific investion - pride, guilt etc., dont correlate with neat physiological measures e.g, heart rate, subjective, humans are good at hiding their emotions, good at lying, but bad at detecting them

supported by yarbrough, 2020

historically argued to reside in evolutionarily older subcortical structures in the brain (the limbic system) - emotions are something thats primitive about us 

emotional displays are due to the primitive parts of our brain taking over - our complex cortices civilise us 

key elements are;

• the hippocampus - memory 
• the amygdala - fear 
• the hypothlamus - the 4 fs

cortical areas are important too;

• cigulate gyrus - autonomic functions such as respiration, heart rate, blood pressure also experience of out emotion 
• parahippocampal gyrus - formation of spatial memory 
• oribitofronal cortex - reward and decision-making, largely active during social situations
• insula, conscious experience

amygdala - quick ealry processing of emotional stimuli 

frontal regions (vmpfc) - intergration of cognition and emotion/conrol of inappropriate emotional reposense, inhibit inappropriate emotional outbursts (cause we've learned from previous experience that this has bad outcomes for us)

insular and cigulate - conscious experience of emotion 

despite these different regions (subcortex, primitative v cortical) being responsible for different elements (the emotion v controlling/regulating the emotion) they are very much interactive 

although many other regions also involved 

early studies of emotion examined lesion and stimulation effect on anials 

e.g., hypothalamus stimulation in cats - fighting or predatory behaviours (e.g., wasman and flynn, 1962

shows importance of hypothalamus in these behaviours in cats - can assume something simialr happenes in humans 

these studies led to early views that the subcortex or 'primative brain' was the 'seat of emotion' 

conversely more advanced cortical 'huamn' elements of cognition reason language etc., were though to be use to override emotion

similarly papes argued that the limbic system was responsible for emotion and the cortex was where it was represented or 'experienced' 

kluver and bucy, '37 

bilateral damage to the amygdala in monkeyd - lack of affect (over emotions) 

no fear response even to innately dangerous obejcts - as well as thing you learn to be afraid off 

also demonstrated the role emotion played in many behaviours;

• not all necessary intuitive 
• animals became indiscriminate in their diet - how does this relate to fear 
• there are certain dangerous foods, you need to be scared to stop from poisoning oneself 
• increased and inappropriate sexual behaviour - guided by fear if we dont control our impulses, it can get us into trouble 
• a tendency to attend and react to all visual stimuli - hard to explain in relation to fear
• oral fixation - regressed to infantile behaviour of exploring the world using thier mouth despite learning that this can be dangerous and shouldnt be done 
• visual agnosia - inability to recognise obhects i.e., recognising the fear stimuli as it is (in humans the amygdala may recognise the object but temporal love may not be able to say why if damaged). in monkeys, they no longer learned fears, as they could not recognise the things they were afraid

difficult to interpret 

quite largw lesions other areas are affected by the lesions - e.g, the temporal lobe, not just the amydala so double dissociation not possible 

could be argued that these behaviours are directly affected byt the lesion rather than due to changes iin the emotional experience - cleary supported by the symptom of visual agnoisa which is a result of damage to the inferor temporal lobes

perhaps these behaviours are directly affected by the lesion rathr than due to changes in emotional experience 

when kb occurs in huamsn through brain lesions, paitents are affected in a similar way to monkeys 

become orally fixated, impervious to fear experience changes in sexual orientation and increased sexual behaviour etc., 

animal studies usggest the frontal lobes are also critical for emotion and emotional behaviour 

frontal lobe lesions in monkeys result in;

• reduced social interaction 
• loss of social dominance 
• inappropriate social interaction 
• altered social preference 
• reduced affect 
• reduced vocalisation 

adding these small individually inconsequential added up can be devestating as if we dont behaviour in the way our social role dictates then were going to lose our social status 

social abilities and emotional abilities are different, but emotions often influence social behaviour - a social ability is to have appropriate emotional responses 

emotion was viewed as a function of the 'primative brain - subcortex 

cortex was involved in higher level cognition functions (e.g., language, logic) which could be used to override emotion 

more recent theories (e.g., damasio, ledoux) - the notion of a primative brain controlling emotion is false. instead emiton is an interactive process between subcortical and cortical structures

the somatic marker hypothesis, - damasio argues that emotion is actually a cogntive process that contributes to logical thinking and behaviour, especially decision making 

general worldview that emotion and logic are diametrically opposed (i.e., head v heart ) - he argued that you use emotion to form your logic 

internal signals from the body (somatic markers) become associated with particular emotions and situations - e.g., increased heart-rate associated with excitement/fear 

emotion circuits in the brain (espeically in vmpfc) represent the somatic markers as emotions - we can sue these internal sensations to guide our behaviour/decisions next time they occur 

rather than having an emotion you feel it subcortex says feel this, and cortex accepts it (i feel this), your body reacts in a physical way to the enviornment and then your brain interprets the info its getting from the body

e.g., seeing a lion running towards you leads to physiological changes in arousal - your cognitive system then interpets these changes as far and responds accordingly 

if this is true removing input from the body shoudl reduce emotion 

work with spinal cord injured patients support this hypothesis 

the higher the spinal cord lesions the less intense experiences of fear and anger are 

damasio extends this hypothesis to a wide of physiological changes - e.g., in the iowa gamgling task 

damasio et al., '94, bechara et al., '97

players choose cards from one of four piles - two high risk, high reward and two low risk, low reward 

other time healthly people will gravate to the low risk, low reward piles as they are logical - vmpfc lesion patients tend to choose the high risk piles, and exhibited typical skin conductance response arousal following wins and losses 

but did not develop anticipatory scrs to the risky deck - risky decks were not assigned somatic markers that discourage healthy people from choosing them by lesion patients 

damasio argues that risky decisions are due to vmpfc patients being unable to utilise the physical cues associated with risk/reward to guide thier behaviours. like in a poker game - choose action with the greatest expected value 

according to damasio, they do this not so much through logical reflection as through the consideration of various options and their bodily response to them 

'it just felt right' - an inarticulate set of logic but the body has accumulated this knowedlge overtime and knows more than the mind can really understand. instead of trying to reason things out using logic they will go with what their body tells them 

gambling addicts and frontal lobe patients are under-sensitive to the pain associated with losing money and oversensitive to the joy associated with the 'big win' - similar to legion patients as the brain isnt working in the optimal manner 

this can be generalised to all sorts of situations - e.g., deciding whether to ask your boss for a promotion, what to eat for dinner etc.

smh implicates vmpfc (as well as sscs, insul, and basal ganglia - depars from the limic theory of emotion

while this theory has intrinsic appeal there are some shortcomings 

much evidence relies on iowa gambling task performance which is affected by multiple other processes e.g., wm and reversal learning (switching away from bad piles);

• if wm is affected by the frontal lobe lesion, they pps may just not have been that good at the game 
• reversal learning - people make an error, and cant help but make that error over an ove
• there are other reason as to why people perfom poorly - that have nothing to do with thier ability to make rational decisions

physiological evidence has been mixed 

ancitipatory scrs may actually reflect reward/punishment expectancies after a decision has been made - pps had sweaty palms when they're about to make a bad decision 

unclear how well smh explains emotion/decision-making in animals 

dunn et al., 2006 critiques

argues that emotion evolved to support survival and that as the brain evolved, cognitive and emotional systems became more interrelated 

ledoux's theory focuses on a single emotion - fear 

in most animals - fear of physical danger 

in humans (and possibly other mammals) - feared stimuli can be broader, e.g., fear of a social situation 

ledoux argues for two types of fear experience in huamns;

• unconscious, automatic fear responses
• conscious awareness of subjective feelings of fear 

days the neural underpinnings of both kinds of fear are similar but slight differences - a fast route/low road and a slow route/high road

ledoux studied responses to threat stimuli and fear conditioning through classical conditioning 

findings suggest the amygdala is the key structure underlying fear - its output leads to the physical responses that the cortex interprets as fear 

monkey with unilateral amygdalectomy - afraid of snakes only when presented on the side projecting to the intact amygdala 

lebar and ledoux, '96 - rats with unilateral amygdala damage had reduced fear conditioning took longer and became less afraid in classical conditioning 

in humans, amygdala damage interferes with recogniton of fear in others

e.g., bilateral amygdala damage - poor perception of fearful facial expressions but in tact perception of happy faces (e.g., adolphs et al., '94) supports the idea that fear is ingrained in amygdala brain cannot recognise, never mind experience fear 

amygdala is connected to many cortical and subcortical regions 

ledoux (2007) - cortical areas seem to be involved in the conscious experience of fear 

frontal lobes implicated - e.g., damage to the orbital and medial pfc, reduced experience of fear/anxiety

having the option of either is a positive as it allows us to respond quickly to innate fears that pose immediate danger, whilst having the slow route you have time to make a logical decision - amygdala can recognise fear associated with non-innate fears through the cortex and respond approrpriate

fast route/high road;

• quick processing of threat stimulus 
• fast auto fear response 
• important for survival 

slow route/high road;

• more detailed and accurate processing of stimulus 
• if stimulus really is threatening, leads to consciously percieved fear 
• if stimulus is not actually threatening can terminate fear response 

how is it the amygdala recognises something as scary 

according to ledoux there are two possibilities - may differ for different stimuli 

genetic explanation and learning explanation 

there may be genetically based neural networks 

the brain is hard wired to respond to dangers 

evidence - soome fears seem to be innate 

e.g., spiders, snakes and heights 

hoehl et a.l., 2017;

• 6 mth olds show increased pupil dilation arousal to images of spiders and snakes than flowers and fish 
• cant guarantee infants had not seen these before but unlikely 

suggests we are predisposed to attend to and learn about threatening stimuli 

expereince can associate stimuli with fear - classical conditioning 

we also learning to fear many things that are not innately dangerous - guns, bombs, etc

the hippocampus, when damaged, interferes with the development of fear responses - healthy people usally learn fear of things through seeing the negative outcomes associated with them 

advantage - explains fear in detail 

disadvantage;

• focuses on only one emotion and does not explain others 
• are these also arising in the frontal lobes, or do they involve other cortical/subcortical structures

gainotti, '72 - cognitive appraisals of emotion depend on hemispheric specialisation 

lh lesions that lead to aphasia are often accompanied by depressive symptoms - or being apathetic 

said the catastrophic reactions were appropriate and indifferent reactions inappropriate for the patients situation 

gianotti suggested rh is dominant for emotion - like lh is dominant for language 

e.g., gazzaniga and ledoux, '78 - in split brain patients, emotional stimuli presetned to the left visual field (so rh) led to emotional responses 

the rh seems specialised for emotional porcesing of faces 

visual scenes presented to the lfv (rh) are viewed as more unpleasant and frigthening than those showed to the rvf (lh)

the left ear (rh) shows an advantage for identifiying the emotional tone of the voice the right ear (lh) is better at recognising content 

people are more expressive on the right side of their face as it directly in the lvf - which is controlled by rh 

the insula has a role in consiously experiencing emotions and internal bodily signals - introception, see craig, 2009 

role in gustatory signals meant it wass originally associated with disgust but not clear role in experiencing all emotional and non-emotional bodily sensations 

craig proposed the right anterior insula to be particularly implicated in emotional experiences 

xue et al., 2010 - fmri study showed emotional responses when choosing to gamble and when winning are stronger in the right than left insula 

just as the production of emotion is important, so is being able to interpret it in others

grynberg et al., 2012 - difficulties understanfin our own emotions are strongly correlated with difficulties recognsing others' emotions 

social skills - recognising others' emotions is important for responding to them appropriately 

damage to various regions can cause emotion recognition deficits 

right amygdala damage impair emotion recogniton - e.g., adolphs et al., 2001 

hronack et al., '96 - ofc damage impairs recognition of others' facial and vocal expressions. but lh lesions dont appear to have as great of an effect as rh lesions 

empathy - sharing anothers' affect, 'mirroring' their emotion in the self 

neural substrates for empathy appear similar to those for experiencing own's own emotion - e.g, amygdala, insula, ofc, and vmpfc 

decety 2011 - review