Fear and Anxiety Flashcards

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1
Q

name the difference between fear and anxiety.

A

fear is a useful and innate response, whereas anxiety is an inappropriate fear response.

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2
Q

give an example of conditioned emotional response.

A
  1. mouse trained to lever press for food.
  2. CS + footshock
  3. normal levels of lever pressing for food in presence of NS
    3b. reduced levels of ever pressing for food in presence of CS.
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3
Q

how many nuclei does the amygdala contain?

A

22

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4
Q

define the clever-bucy syndrome.

A

disorder that occurs when both the right an left medial temporal lobes of the brain malfunction.

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5
Q

when amygdala was removed from temporal lobe, what was the outcome?

A

lack of fear response.

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6
Q

give evidence that amygdala s involved in fear?

A
  • less amygdala leads to less fear
  • increased activation during public speaking in subjects with SAD.
  • activation following presentation of fearful stimuli.
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7
Q

state the three types of symptoms of anxiety.

A
emotional = fear
cognitive = anxious thoughts 
somatic = increased heart rate
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8
Q

what parts of the brain does the amygdala activate?

A

coeruleus and hypothalamus.

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9
Q

describe the HPA axis.

A

H-hypothalamus releases CRH
P-pituatary releases ACTH
A-adernal cortex releases cortisol and adrenaline

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10
Q

what does lock coeruleus release?

A

noradrenaline.

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11
Q

name states of sympathetic nervous system.

A
  • increased heart rate
  • blood pressure
    = prepares brain for situation e.g run faster away from threat
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12
Q

name states of the central nervous system.

A
  • behavioural arrest and arousal

- cortisol activation

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13
Q

describe the role of the GABAergic system in regulating fear/anxiety.

A

evidence of GABA disfunction in anxiety disorders.

  • panic disorder patients have less BZD binding sites.
  • panic disorder patients lack sufficient inhibitory control in corticol and limbic regions to suppress inappropriate fear responses.
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14
Q

what occurs in the presence of BZDs as a drug?

A
  • GABA molecules are more effective at opening CL- channel
  • greater influx of chloride
  • greater hyperpolarisation
  • more inhibition
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15
Q

what type of structure do GABAa receptors have?

A

heteropentameric structure.

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16
Q

state drugs that increase GABAa receptor activity and so reduce anxiety.

A
  • agonists = alcohol and barbiturates

- indirect agonist = BZDs

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17
Q

state drugs that decrease GABAa receptor activity and so increase anxiety.

A
  • antagonist = flumazenil

- inverse agonist = beta-CCM

18
Q

state side effects of BZDs

A
  • anxiolytic
  • anticonvulsant
  • sedative
  • muscle relaxant
  • amnestic
19
Q

describe what the alpha reactors of BZDs show.

A

a1 - everywhere high in cortex
a2 -limbic structures, hippocmapus, amygdala
a3 - reticular activating structures brain stem basal forebrain, spinal cord
a4 - hippocampus, spinal cord

20
Q

describe the elevated and maze study.

A
  • UR to potentially dangerous environment
  • anxiety = degree to which animal acids the open arms (less anxious, more confident to explore)
  • effect of diazepam = increase in amount of time spent in open arms of the maze.
  • drug specific to a2 receptors reduce anxiety as more mice explore open arms!
21
Q

a suppression ratio of 0 indicates…

A

an anxious state.

22
Q

a suppression ratio of 0.5 indicates…

A

not anxious state.

23
Q

describe what occurs in the absence of alpha 2 receptors that indicate it is involved in anxiety.

A
  • no difference in acquisition or lever pressing for food before footshock is present
  • more anxiety in alpha 2 knockout mice than wildtype when shock is present.
  • BZDs reduces suppression in wildtype but not knockout mice.
24
Q

what type of subunit had no anxiolytic effect?

A

a2 alpha receptor.

25
Q

describe the structure of the GABAa receptor.

A
  • protein structure
  • 5 protein submits around a central ion (CL- channel), each consists of 4 transmembrane domains.
  • extracellular tail
  • intracellular loop
26
Q

where do BZDs bind?

A

histidine in N-temrinal extracellular domain.

27
Q

what specific subtype show a good effect?

A

alpha 1 receptor - causes anxiolytic effect but not sedation.

28
Q

describe the association between BZDs and the amygdala.

A
  • high density of BZD binding sites in amygdala.
  • injection of soluble BZD into amygdala induces an anxiolytic effect
  • injection of BZD antagonists not amygdala abolishes anxiolytic of a benzo given systematically.
29
Q

describe the hippocampus role in anxiety.

A
  • diminished activity of hippocampus can result in anxiety.
  • lesions have anxiolytic effects
  • Benzos can have a direct effect on GABA inhibition in hippocampus
  • decrease in fear response when midazolam is administered to hippocampus
30
Q

in situations of chronic stress, chronic activation of glucocorticoid receptors in hippocampus leads to…

A
  • increased Ca2+ entry into neurons

- too much Ca2+ = excitotoxic = cells die

31
Q

name systems what the amygdala and hippocampus respond to.

A

modulatory systems:
- noradrenergic system = arousal and attention
- serotonin system = mood and emotion
= thought to balance one another.
- deregulation of systems can result in fear and anxiety.

32
Q

give evidence that the locus coeruleus is involved in anxiety.

A
  • events that are important for survival causes increased firing of LC which increases arousal and attention.
  • Benzos decrease the release of noradrenaline in the LC
33
Q

give evidence that the raphe nuclei is involved in anxiety.

A
  • punishing stimuli activate the serotonergic system which leads to behavioural inhibition.
  • benzos decrease the serotonergic activity.
34
Q

where does the LC project to?

A

noradrenaline projections to cerebellum, hippocampus, neocortex and thalamus.

35
Q

where does the raphe nuclei project to?

A

serotonergic projections to striatum, nucleus accumbens, frontal cortex and hippocampus.

36
Q

anxiety associated with arousal is mediated by…

A

brain noradrenergic systems.

37
Q

anxiety associated with behavioural inhibition is mediated by…

A

brain serotonergic system.

38
Q

give common treatments for specific anxiety disorders.

A

BZDs - GAD and PD
SSRIs - OCD, PTSD, PD, GAD
Buspirone - GAD

39
Q

SSRIS prolong action of …

A

5-HT in synapse

40
Q

describe the function of buspirones.

A
  • 5 HT1A agonist
  • somatodendritic receptors
  • decrease 5-HT cell firing
  • no symptomatic change util weeks int treatment.