Anxiety Disorder 1 Flashcards
What is pathologica anxiety and what are its:
- components
- patterns
- signs
(4 marks)
- Pathological anxiety: An exaggerated fear state in which there is hyperexcitablity of fear circuits including the amygdala and extended amygdala
- Components: apprehnesion, nervous
- Patterns: generalised - may last hours, days not to specific threat and paroxysmal (abrupt, onset, episodic)
- Signs: tachycardia, palpitations
What are some of the simliarities and differences between fear and anxiety?
(4 marks)
Similarities:
- Presence/ anticipation to danger
- Elevated arousal
- Negative affect
- Bodily sensations
Differences:
- Anxiety:
- quality of sustained vigilance
- no presentable/ identifiable threat
- Fear:
- reasonable connection to threat
- identifiable threat
- no quality of sustained vigilance
Around which age period does the onset of anxiety tend to occur?
- During childhood
With which other mental illness does anxiety tend to share cormobidity with?
(1 mark)
Depression - tend to be treated very similarly - belived that one or other is primary/ secondary condition
What are the 3 forms of anxiety?
(3 marks)
- Behavioural activation system
- Behavioural inhibition system
- Fight/flight system
What is the behavioural activation system?
(2 marks)
- Reward system - teaches you that behaciour can affect your mood
- Involves the neocortex, VTA, striatum and is sensitive to appetitive or reward behaviour
What is the behavioural inhibtion system?
(2 marks)
- Punishment system
- Involves ARAS, brainstem neocortical projection from cortex
- Responsive to punishment novelty and uncertainty
ARAS = acending reticular activating system
What is the fight/flight system?
(2 marks)
- Threat
- alteration here may cause anxiety
What is the ‘Uncertainity and anticiptiation model of anxiety’ (UAMA)?
(1 mark)
- Shows an increases threat expectancy which isn’t real and is harder to treat
What are the five processes underlying the ‘uncertainty and anticipation model of anxiety’?
(5 marks)
- Inflated estimates of threat cost and probability
- Increased threat attention and hypervigilance
- Deficient safety learning
- Behavioural and cognitive avoidance
- Heightened reactivity to threat uncertainty
What key brain regions are implicated in maladaptive responses to anxiety in UAMA?
(7 marks)
- Amygdala
- Bed nucleus of Stria terminalis
- Ventral prefrontal cortex
- Dorsomedial and dorsolateral prefrontal cortex
- Orbitofronal cortex
- Anteriror insula
found implication of BNST??
What structural changes can be seen in anxiety and what has fMRI shown?
(4 marks)
- Increase in amygdala and hippocampal volume and activation
- Increased connectivity in PFC with amygdala and anterior hippocampus
- Activation of BNST - BOLD signal showed activity here is altered and the way BNST processes information in response to threat is altered
In which brain regions can activity be seen under these tages of anxiety:
- Inflated estimates of threat
- Increased threat attention hypervigilance
- Deficient safety learning
- Avoidance
- Increase reactivty to uncertainty
(5 marks)
- Increase in activty in PFC
- Increase in acitivity in the amygdala
- Affects vmPFC
- Affecting dlPFC first
- Affects BNST which modulates fear system responses
Give examples of animal fear models to test fear.
(2 marks)
- Pavlovian fear conditioning
- Acoustic startle response
Give examples of animal models for stress,
(2 marks)
- Measuring plasma hormones (glucocorticoids)
- Measuring vital signs
Give a few examples ofr animla models for anxiety.
(4 marks)
- Hyponeophagia (a measure of anxiety in a mouse)
- Active avoidance
- Elevated maze - mouse gets conflicting drives to explore novel spaces and avoid open ones
- Social tests - place in box with another mouse and see if they remain in ‘social’ area or isolated one
What is the fear potentiated startle in animals?
(3 marks)
- Condition animal to light foot shock - fear learning
- Play the unconditioned fear response - sound and light = startle
- Pair the CS and US get increased startle amplitude and increased anticipatory anxiety
What would be seen from a lesion in either the central amygdala or bed nucleus of stria terminalis? What are the implications for fear learning?
(3 marks)
- Lesion in either region would result in a reduction of the release of corticotrophin hormone
- BNST is key for anxiety and through a light/ CRH enhanced response you’ll see a reduction in the activity in BNST
- CeA is essential for the fear response but in a lesion under the fear potentiated state you’ll see a reduction in actiity in CeA
Where do the BSNT and teh CeA receive projections from and what do they do?
(1 mark)
- Recieve projections from the BLA and in turn project downstream to modulate behavioural and electrophsyical consequences of fear and anxiety
What was seen by channel rhodopsin-2 assisted circuit mapping?
(2 marks)
- Revealed that both BNST glutamate and GABA projects preferentially to innervate post synaptic non-dopaminergic VTA neurons
- This provides mechanistic framework for in vivo, circuit pertubatinos
Outline the neuromacrocircuitry of anxiety (long range circuits).
(4 marks)
- DA projections originate in the VTA and project to the NAc, mPFC and BLA - modulate glutamate and GABA transmission
- Glutamate projections from mPFC, BLA & VHC, converge onto MSNs of NAc and from LHb (lateral habenula) onto GABA neurons on the tail of VTA
- GABA transmission of MSNs and BNSTs inhibts cells in VTA causing disinhibtion
What components make up the amygdalo-centric view of fear?
(5 marks)
- LA - activity dependent associative synaptic plasticity occurs here - essential for classically conditioned response
- [in BLA and auditory cortex] - suppression of dendritic inhibtion mediated by somatostatin interuons.
- disinhibition in hipocampu_s may block contextual fear conditioning (in unconditioned averisve stimuli h_ippocampal somatostatin neurons inhibit dendrites of CA1 porjection neuron preventing plasticity)
- reciprocal connections between BLA and its targets, suggest networks organised in loops
