Anxiety

Question 1

WHat is context?

Answer 1

the internal (cognitive and hormonal) and external (environmental and social) backdrop against which psychological processes operate

Question 2

WHat is context encoding?

Answer 2

animals first encode a representation of the context (when the animal explores the context before a footshock

Question 3

WHat is context conditioning?

Answer 3

then associate that representation with the US

Question 4

Context encoding brain areas and evidence

Answer 4

• Hippocampus
• hippocampal lesions in rodents produce deficits in freezing behaviour during exposure to a shock-paired context
• These deficits are especially robust when hippocampal lesions are made soon (1 day) after contextual fear conditioning but are minimal when lesions are made at later times
• Deficits in context fear memory following hippocampal damage appear to be due to a deficit in forming and storing the contextual representation itself (that is, in context encoding)
• Responds a lot to locations in space
• Deficits to the entorhinal, perirhinal, and postrhinal cortices that input to hippocampus mimic hippocampal deficits

Question 5

context storage brain area

Answer 5

• Anterior cingulate cortex ACC
• Inactivation of this area impairs the expression of remote context memory
• ACC neurons exhibit greater activity during retrieval of remote relative to recent context fear memories
• cortical areas with which the hippocampus is reciprocally connected may be essential for maintaining context representations over time.

Question 6

5HT1A receptor in Anxiety

Answer 6

• High density of these in cortical and subcortical areas and considered the major inhibitory serotonergic receptor
• High in limbic, temporal and prefrontal cortices
• Plays a role in fear, aggression, and impulsivity
• the lower tracer binding of the receptor observed in patients with psychiatric disorders, when compared with control subjects

Question 7

Presynaptic 5HT1A

Answer 7

• Raphe nuclei somatodendritic autoreceptors

- Activation of these receptors causes a reduction in firing, synthesis, turnover, and release of serotonin

Question 8

Postsynaptic 5HT1A

Answer 8

• Located in glutamatergic and GABAergic neurons in limbic and entorhinal cortices
• Modulate serotonin sensitivity and involved in emotional and cognitive processes

Question 9

5HT1A Knockout mice

Answer 9

• Increase in anxiety level and behavior is present in homo and hetero knockout mice
• Indicates a partial receptor deficit is sufficient for anxiety
• Receptor down regulation is risk factor with psychiatric disorders
• Mice with the genetic deletion of the 5-HT1A receptor were shown to be more fearful in a number of behavioral conflict tests

Question 10

Amygdala and anxiety

Answer 10

• 5HT1A agonists injected into the amygdala produce anxiogenic effects (anxiety causing effects)

Question 11

SSRI’s

Answer 11

• act by selectively blocking the reuptake of 5-HT following its release from neurons, thereby changing 5-HT neurotransmission in the brain, including binding on the 5-HT1A receptor
• First-line treatment of anxiety disorders

Question 12

Benezodiazepines 5HT1A and GABA

Answer 12

• Anxiety disorders are commonly treated with benzodiazepines that bind to GABAA receptors
• 5-HT1A receptor knockout mice display benzodiazepineresistant anxiety
• Lower GABA brain levels consistent with anxiety disorders
• GABA A receptor role in anxiety
  
  • Linked with sedative effect of benzodiazepines