emotion - week 9 part 2 Flashcards
what is emotion regulated by?
the brain
evidence for the brain regulating emotion
clinical observations of patients with neurological damage
- in some cases the consequences of brain damage include an alteration in emotional behaviour and feelings
evidence for the brain regulating emotion
phineas gage
tamping rod through cortex
acident destoryed part of his pre-frontal cortex
unaffected speech, intelligence and memory
seemed to aquire a different personality
- described as reflecting dominance of animal propensities
evidence for the brain regulating emotion
vietnam war veterans
who suffered traumatic damage to ventral preforntal cortex revealed a greater propensity for aggressive and violent behaviour
evidence for the brain regulating emotion
monkeys (1939)
bilateral temporal lobectomies in 15 rehesus monkeys and one cebus monkey
no. of emotional changes (klüver - bucy syndrome in humans)
became tame with an absence or great reduction in fear and anger related behaviour and vocal responses
no hesitation in approaching new objects, animals and people
- normally display substatial neophibia which protects against harm from objects
evidence for the brain regulating emotion
superficial conclusion
temporal lobe and ventral prefrontal cortex mediate -ve emotions
–> fear and anger
however clear from other observations of monkeys showed changes in emotional behaviour were not limited to negative emotions
–> eg. increase in frequency and duration of sexual activity
- implicating the human ventromedial prefrontal cortex in social reward
- human participants showed activation when they were led to believe they were liked by people they admired
evidence for the brain regulating emotion
2 possible interpretations
- different areas within regions of interest mediate the different emotions
- individual brain areas serve common functions different emotions
limbic system
what?
the areas of the brain that mediate emotion
has been modified to accomodate brain areas that have emerged as being important in emotional function
eg. shell of nucleus accumbens (rewards) and cortical areas beyond the cingulate cortex
- this is to ensure the concordance between limbic system and emotion
therefore to say emotion is mediated by the limbic system is a truth that is ensured by its definition as the system that comprises the areas involved in emotion
the amygdala
implicated in what behaviour?
fearful
the amygdala
anatomy
almond shaped structure
deep within temporal lobe
recieves sensory inputs from all modalites
- info arrived both directly from sensory thalamus and also from sensory cortical areas
in a position to coordinate patterns of response
the amygdala
anatomy - downstream
no. of regions w/ functions related to emotional biological responses
- lateral hypothalamus –> HR and blood pressure
- paraventricular nucleus –> release of stress hormone
- periaqueductal grey matter –> freezing response
does the stimulation of the amygdala effect emotional responses?
if amygdala is connected to brain areas responsible for producing emotional responses, it follows that if we stimulate the amygdala this should produce activity downstream in regions t result in emotional states
does the stimulation of the amygdala affect emotional responses?
evidence - monkeys
1964
amygdala stimulation results in increase in HR
does the stimulation of the amygdala affect emotional responses?
evidence - rats
1964
increase HR and blood pressure
1986
corticosterone release into bloodstream
1988
produces fear like behaviour - acoustic startle reflex
does the stimulation of the amygdala affect emotional responses?
evidence - humans
amygdala stimulated in epilect patients
patients reported feeling their heart beating faster and some reported feelings of anxiety or fear
- other studies found might just be fearful of procedure itself
- only a subset of patients experienced these feelings
stimulating amygdala in aggressive patients led to aggressive behaviour
- possible that cognitive context affects the subjective impact of amygdala stimulation
these studies did not take physiological measurements of cardiovascular responses, so cannot make any links between these subjective feelings and any biological responses
does damage to amygdala impair normal emotional response?
just amygdala?
because small and 2cm3 deep in temporal lobe damage from stroke, trauma or surgical resection not limited to amygdala
- also impacts overlying cortex and hippocampus
does damage to amygdala impair normal emotional response?
selective amygdala degeneration
urbach-wiethe disease
patient SM
- appears to show little/no experience of fear
2011
despite hating snakes and spiders showed no hesitation in touching them showing a distinct lack of fear and avoidence
no fear when visiting haunted places
when repeatedly tested on standard questionnaires of fear and anxiety over 3 years scored consitatntly at a much lower level than controls
SM cannot be described as emotionless as she reported high levels of excitement in the haunted house therefore suggesting amygdala plays a role in subjective fear
first implication of amygdala in fear
mid 20thC
bi-lateral lesions to amygdala
- monkeys were tame and showed little neophobia
- showed impairments in experimental fear memory paradigms
—> conditioned avoidance and supression tasks
- light/sound and footshock
- marked reduction in avoidance and supression compared to controls
rats 1990
auditory information must be sent from the thalamus to some other region (primary canditate amygdala)
amygdala and emotional memory
study of SM
looked at her capacity to acquire conditioned fear responses
looked at SM’s physiological galvanic skin response to colours associated with an aversive startling sound
SM showed no evidence of a physiological emotional response –> controls did
amygdala and emotional memory
does impairment of normal amygdala function in experimental animals disrupts fear learning and memory?
huge amount of evidence to suggest yes
however the interpretation of effects on memory of permanent brain damage is complicated
–> reversible brain damage preferable but not current way to do this
amygdala and emotional memory
human functional imaging studies
focused on direct fear processes –> recognition
the amygdala is activated by exposure to fearful facial expressions and this activation is thought to be a necessary mechanism in processing fearful stimuli
urban-wiethe patients are impaired in the recognition of fear in facial expressions
however, while the recognition of fearful expressions may be supported by prior experience + learning it is not obvious from such studies that the amygdala necessarily plays an important role in fear learning and memory
amygdala and emotional memory
pavlovian conditioning procedures 1998
what?
used faces as stimuli - but had neutral expressions and they conditioned them such that the conditioned faces were paired half the time with an unpleasant tone
–> control faces were never paired w/ adversive outcome
amygdala and emotional memory
pavlovian conditioning procedures 1998
was the amygdala activated?
amygdala was activated on both sides during learning of conditioned faces and this activation corrolated w/ magnitude of skin conductance
provides strong evidence amygdala is critically invloved in fear learning in relation to facial stimuli it does not rule out possibility that the human amygdala is somehow specialised for emotional faces
amygdala and emotional memory
1998 - coloured squares + electric shock
shows?
showed same patterns of amygdala activation and skin conductance
amygdala and emotional memory
1998 - coloured squares + electric shock
means?
that involvement of amygdala in fear learning + memory is not limited to specific stimuli and outcomes
assumption is that synaptic plasticity (some) is taking place in the amygdala that mediates the learned fear and this plasticity process is reflected in the enhanced amygdala activity
amygdala and emotional memory
human and animal research
while studies of human fear conditioning seems to corroborate what is known from animal research
- aspects of human emotional learning that can only be studied in humans
- we can simply be instructed to fear a stimulus
- in an experimental situation subjects are told that one stimulus might be associated with a shock whereas, the other stimulus was completely safe
- despite never being any shock presentation of stimulus elicited activity in the left amygdala correlated w/ emergence of skin conductance
amygdala and emotional memory
significance of amygdala activation being unilateral when being told to fear in comparison to bilateral in standard fear conditioning?
not clear
however the existence of an apparently normal fear response after simple instruction may explain how fears can be acquired in a purely social manner
beyond fear
amygdala also involved in positve reward-related pavlovian conditioning
–> cue induced addictive drug seeking is associated with amygdala function
beyond fear
behaviour of drug addicts
rodents
the behaviour of drug addicts to seek and take drugs is profoundly under the control of the stimuli that has previously been associated with the drug
rodent models
- exposure to drug associated stimuli activates the amygdala and lesions distrupt cue-induced drug seeking
beyond fear
behaviour of drug addicts
functional imaging in humans (1999)
show that when abstinent cocaine addicts are shown videos of cocaine - related stimuli the amygdala is significantly activated compared to a neutral vid condition
replicated using subliminal presentations of drug related stimuli
- showing that the pavlovian control of drug seeking behaviour occurs at a subconscious level
amygdala was activated for each of the motionally relevent stimuli compared to the neutral control
–> regardless of the emotional valence of the stimuli
–> therefore amygdala not only important for fear but other +ve emotions as well
is the amygdala’s role in learning + memory limited to non-declarative pavlovian memories?
colours and shock study.
- amygdala role in concious memories?
patient SM compared to patient WC (damaged to hippocampus)
WC normal when tested on galvanic skin response
however has no conscious memory of which colour were associated with the adversive tone
in contrast too SM shows no skin response but could remember the colours
–> this might suggest that the amygdala has no role to play in concious memories
is the amygdala’s role in learning + memory limited to non-declarative pavlovian memories?
amygdala’s role in memory of real life events
amygdala seems to play important role in memories for real life events
SM exhibited a dispassionate recollection of traumatic life episodes and a study of japanese Alz patients provides strong evidence that defictsin real-lie emotional memory result from a distruption of amygdala rather than hippocampal function
is the amygdala’s role in learning + memory limited to non-declarative pavlovian memories?
amygdala’s role in memory of real life events
- 1999 alz patients questioned on events on Kobe earthquake (1995)
accuracy was correlated w/ neurodegredarion of different regions
degeneration in amygdala strongly predictive of poor declarative emotional memory
damage to hippocampus seemed to bare no obvious relationship to accuracy
therefore amygdala is important for declarative as well as pavlovian memories
–> clearly doesnt operate in isolation
downstream of amygdala
amygdala projects to a no. of brain areas
- each of these associated w/ a particular emotional response
downstream of amygdala
the periaqueductal grey (PAG)
PAG region in midbrain recieved strong projections from amygdala
- specifically invloved in the behavioural response of freezing when fearful
downstream of amygdala
does stimulation of amygdala activate PAG
can be done electrophysiologically
showing that amygdala activation leads to electrical activity in PAG
can be done cellularly
- using the activation of gene expression as a marker
most relevant evidence is the behavioural evidence
downstream of amygdala
does stimulation of amygdala activate PAG
behavioural response
amygdala activation –> fearful response
1997 - freezing behaviour - must be PAG
this is not clear
–> direct stimulation or chemicals that elict neuronal activity
sometimes freeze but also active responses (running + jumping)
downstream of amygdala
why does response to PAG stimulation vary?
PAG is not a homogeneous structure
can be broken down into sub-divisions
ventral portion, vlPAG
dorsal portion, dlPAG
downstream of amygdala
vlPAG vs dlPAG
2001
vlPAG stimulation = freezing behaviour (rats)
dlPAG stimulation = active responses (mechanism unclear)
downstream of amygdala
does amygdala primarily project to vlPAG or dlPAG
vlPAG
can conclude that behavioural freezing response to fear that is triggered in the amygdala is mediated downstream by the vlPAG
supported by lesion studies to vlPAG which show a selective loss of the freezing response to innate and learned stimuli without effecting other classes of fear responses
upstream from amygdala
the prefrontal cortex (PFC)
upstream from amygdala
the prefrontal cortex (PFC)
emotional behaviour is complex and requires top-down relgulation
PFC source of many inhibitory projections to subcortical brain areas
- in particualr connection between ventral PFC (mPFC in rodents) and the amygdala
therefore would expect that is this inhibitory influence were to be removed amygdala mediated emotional responses would run unhindered
–> this is essentially what is believed to be the problem in PTSD with the failure to regulate and inhibit fear processing leading to clinical anxiety
upstream from amygdala
the prefrontal cortex (PFC)
evidence?
whole field that looks into role of PFC in fear memory extinction
- a reduction in pavlovian or instrumental memory when the conditioned stimulus or action is no longer associated with the outcome
the fear extinction memory results in the supression of fear expression in a process that critically depends on mPFC in rodents
so mPFC has a functional role to play in regulating fear expression
upstream from amygdala
the prefrontal cortex (PFC)
mPFC lesions extended to non-fear memories?
2007
lesions in the mPFC result in impaired memory extiction in a procedure in which rats learn that a tone predicts delivery of food
so approach food on hearing the tone
normally this behaviour can be extinguished and only recovers in the normal manner
rats with mPFC lesions recovered the food-related response more readily
- indicating an impairment in the inhibition of the original pavlovian memory
memory extinction
Reduction in pavlovian or instrumental memory expression when the conditioned stimulus (CS) or action is no longer associated with the outcome.
upstream from amygdala
the prefrontal cortex (PFC)
why is generalisation across memory types important?
this generalisation is important because we cannot therefore conclude that the mPFC is involved in specific emotions
especially important when looking at evidence from humans
upstream from amygdala
the prefrontal cortex (PFC)
study of aggressive subjects 2001
antisocial behaviour were identifed as a problematic consequence of PFC damage
the link between PFC and aggression not limited to cases of brain damage
natural variation in the structure and function of the PFC may underlie differences in aggressive behaviour with clinical and other serious consequences
upstream from amygdala
the prefrontal cortex (PFC)
grey matter + PFC (2000)
patients with antisocial personality disorder have a reduced vol. of grey matter in the PFC
the structural abnormality has a functional consequence as evidenced by the fact teh perpretratiors of violent murders have lower functional activity in the PFC compared to controls (PET scans 1997)
upstream from amygdala
the prefrontal cortex (PFC)
grey matter + PFC (2000)
patients with antisocial personality disorder have a reduced vol. of grey matter in the PFC
the structural abnormality has a functional consequence as evidenced by the fact teh perpretratiors of violent murders have lower functional activity in the PFC compared to controls (PET scans 1997)
upstream from amygdala
the prefrontal cortex (PFC)
what is it doing?
PFC appears to be acting in a inhibitory manner
suppressing aggressive behaviour
a reduction in the capacity of the PFC to carry out this function (damage or other variations) result in an increase in aggression
upstream from amygdala
the prefrontal cortex (PFC)
can we conclude that PFC is selectively involved in aggression?
inconsistent with animal literature suggesting a generalised role in emotional regulation
extensive evidence in humans to indicate important role in fear inhibition
- functional imaging of fear memory extinction implicates human ventral PFC and amygdala
- the strength of the connection between vPFC and amygdala appears important for normal function
- magnetic resonance imaging can not only be used to identify increased blood flow to infer localised brain activation but also to establish the strength of functional connectivity between two brain areas (diffusion tensor imaging)
upstream from amygdala
the prefrontal cortex (PFC)
study 2009
strength of vPFC and amygdala pathway
extensive evidence in humans to indicate important role in fear inhibition
- functional imaging of fear memory extinction implicates human ventral PFC and amygdala
- the strength of the connection between vPFC and amygdala appears important for normal function
- magnetic resonance imaging can not only be used to identify increased blood flow to infer localised brain activation but also to establish the strength of functional connectivity between two brain areas (diffusion tensor imaging)
used these approaches to show that the strength of the vPFc - amygdala pathway was inversely correlated with an assessment of trait anxiety
- hence stronger connection of vPFC and amygdala presumably resulting in a greater capacity of prefrontal inhibition of amygdala function (the lower likelihood of anxiety)
upstream from amygdala
the prefrontal cortex (PFC) much more complex than simple inhibition
with an established link to exeuitive functions it would seem logical that the PFC might use emotional information in order to influence decision making
first evidence to support this comes from phineas gage
- damage to PFC didnt simply result in a loss of behavioural inhibition and capacity for extinction nut impacted his behaviour more widely
- this has been characterised as a state of risky decision making in absence of normal vPFC function
hence the vPFC serves a complex higher-order function in relation to emotional processing
how does the amygdala, PAG and PFC tie together?
projection and amygdala to PAG allows response to be expressed
influence of PFC puts a break on this (so not over expressed)
in order to have an adaptive emotional response the coordinated activity is important
how do we communicate emotions?
changes in posture
changes in facial expression
–> the 6 core emotions
why is it important to communicate emotions?
need to be consistent and rapid
socially
avoiding danger
emotional facial expressions are :
- automatic
- biological
- unconscious
- possibly innate
how is consistent emotional facial expression achieved?
development of facial expressions emerged through evolutionary processes
as a consequence if facial expressions have an evolutionary basis then they are determined by genetic and biological processes
hence emotional facial expressions should have a biological underpinning
neural basis of facial expression
they are automatic and involuntary
neural basis of facial expression
volitional facial paresis
causes: damage to region of motor cortex controlling face muscles or to neurons connecting the two
effects: cannot voluntarily control facial expressions, involuntary still happens
neural basis of facial expression
emotional facial paresis
cause: damage to specific region of PFC or to thalamic region between PFC and hindbrain regions controlling musculature
effect: emotions do not elicit facial expressions even though person can voluntarily make component movements
neural basis of facial expression
facial paresis (hemispheric) 1998
only seen in one side of the face
- can learn that the voluntary control of our facial muscles is different from the automatic production of emotional facial expressions
facial expressions in non human animals
- what does this mean?
drawings and photos used by darwin to illustrate similarities in emotional expression meaning:
- there is an evolutionary basis
- they have an hereitary compenent
- they have a genetic component
- they are biological
therefore not purely a social construct
humans dont have facial expressions simply because it is socially expected
facial expressions in non human animals
- any social contribution?
doesnt mean that there is no social contribution rather that the underpinning ability is biological in nature
suggesting that facial expressions are innate
are facial expressions innate responses?
does the biological basis make it innate or does it mean we are born with the capability of learning appropriate facial expressions
are facial expressions innate responses?
cross-cultural generality (1971)
trail engaged w/ tribes in papa new guinea
recognition of emotional facial expressions correct
- so in cultures w/ no interaction to other cultures develop same social expressions
so must be innate otherwise expressions would diverge
are facial expressions innate responses?
facial expressions in congenitally blind people (2006)
facial expressions both recognisable and more similar to family members than to non-relations
suggesting hereditary and genetic
facial expressions not global?
does this mean not innate?
complex interaction between innate and learned social mechanism?
facial expressions in new borns?
are present early in life
feedback from family members (auditory feedback)
