Fear and Anxiety

Question 1

what are anxiety disorders?

Answer 1

excessive or maladaptive fear response

Question 2

what are the two areas of the brain that have been found to play a role in fear and anxiety?

Answer 2

the amygdala and the hippocampus

Question 3

where is the amygdala located?

Answer 3

deep in the temporal lobe

Question 4

describe evidence that the amygdala is involved in fear

Answer 4

kluver-bucy syndrome is a disorder that occurs when both the right and left medial temporal lobes of the brain malfunction. it results in little to no fear response

Question 5

describe evidence that the amygdala is involved in anxiety

Answer 5

in participants with social anxiety disorder there is increased amygdala activation when public speaking compared to speaking in private

Question 6

describe evidence that the hippocampus is involved in anxiety

Answer 6

hippocampal lesions have anxiolytic effects

Question 7

what part of the nucleus activates fear related behaviour?

Answer 7

the central nucleus

Question 8

what is the HPA axis?

Answer 8

the hypothalamic pituitary adrenal axis - controls the release of glucocorticoid hormones

Question 9

which glucocorticoid is involved in anxiety?

Answer 9

cortisol (a stress hormone)

Question 10

describe the process of the HPA axis

Answer 10

the hypothalamus releases corticotrophin-releasing hormone (CRH)
this stimulates the pituitary gland to secrete adrenocorticotropic hormone (ACTH)
this stimulates the adrenal cortex to release cortisol and adrenaline

Question 11

describe how the locus coeruleus is involved in anxiety

Answer 11

the LC releases noradrenaline which stimulates the fight or flight response or freeze response

Question 12

provide evidence that GABAergic disfunction plays a role in anxiety disorders

Answer 12

benzodiazepines are the most effective anxiolytic drug
patients with panic disorder have less benzodiazepine binding sites (PET study with radiolabelled flumazenil - indicating benzodiazepine binding sites)

Question 13

what is the structure of GABA A receptors?

Answer 13

heteropentameric structure - 5 binding sites

Question 14

what is the amygdala’s role in anxiety?

Answer 14

sensory information is channelled to the amygdala, the amygdala then excites the hypothalamus and the locus coeruleus

Question 15

what are drugs that increase GABA A receptor activity called?

Answer 15

anxiolytics - reduce anxiety

Question 16

what is the difference between a direct and indirect agonist?

Answer 16

direct = binds to the receptor and acts as a neurotransmitter
indirect = increases and enhances the amount of neurotransmitters affected but has no effect on the receptor

Question 17

what are examples of direct and indirect GABA A receptor agonists?

Answer 17

direct = alcohol, barbiturates 
indirect = benzodiazepines

Question 18

what are anxiogenic drugs?

Answer 18

drugs that decrease the GABA A receptor activity and increase anxiety

Question 19

give some examples of antagonist and inverse agonist anxiogenic drugs

Answer 19

antagonist - flumazenil

inverse agonist - beta CCM

Question 20

what is the difference between antagonists and inverse agonists?

Answer 20

antagonists = bind to receptor and block other molecules from binding, but have no effect on receptor activity
inverse agonists = binds to receptor and has prevents receptor activity

Question 21

what is the elevated + maze?

Answer 21

a study testing the effects of benzodiazepines in rats. measures an unconditioned response to a potentially dangerous environment
diazepam increases the amount of time spent in the open arms of the maze (less anxiety)

Question 22

which GABA A receptor subtype is most active in anxiety responses and provide evidence?

Answer 22

alpha 2 subunit 
knockout mice (with the alpha 2 receptor removed) show more anxiety than the wildtypes (without the receptor removed)

Question 23

what is the benefit of narrowing down the receptor subtypes that mediate anxiolytic effects?

Answer 23

drugs can be developed that target these subtypes which will produce anxiolytic effects without side effects

Question 24

where is the highest density of benzodiazepine binding sites?

Answer 24

amygdala

Question 25

provide evidence for the role of the hippocampus in anxiety responses?

Answer 25

hippocampal lesions have anxiolytic effects, BZ also have a direct effect on the GABAergic inhibition in the hippocampus

Question 26

what happens in situations of chronic stress?

Answer 26

there is a chronic activation of glucocorticoid receptors in the hippocampus, which results in increased calcium entry into neurons. too much calcium can be excitotoxic, and result in cells dying. this means that the hippocampus can’t feedback to limit cortisol production

Question 27

what are some causes of anxiety disorders?

Answer 27

diminished activity of hippocampus, loss of feedback to amygdala, inappropriate fear responding

Question 28

what diffuse modulatory systems also play a role in inappropriate fear and anxiety responses?

Answer 28

noradrenaline (arousal and attention) and serotonin (mood and emotion)

Question 29

describe how noradrenaline affects the Locus Coeruleus

Answer 29

increased activity of noradrenaline in the LC = increased arousal and attention

Question 30

how do benzodiazepines affect noradrenaline?

Answer 30

they decrease the release of noradrenaline in the locus coeruleus

Question 31

what do raphe nuclei do?

Answer 31

produce serotonin

Question 32

how do benzodiazepines affect serotonin?

Answer 32

they decrease the serotonergic activity in the raphe nuclei

Question 33

what anxiety response does the noradrenergic system modulate?

Answer 33

arousal - fight or flight

Question 34

what anxiety response does the serotonergic system modulate?

Answer 34

behavioural inhibition - freezing