Serotonin (Lect 4)

Question 1

Serotonergic systems

Answer 1

• originate in brain stem + project axons through brain
• mainly inhibitory effects on higher brain regions
• increase of serotonin –> decreased behavioral activation + arousal
• plays role in: mood, memory, sleep, appetite, pain perception and temp regulation

Question 2

5-HT Neuron

Answer 2

5-HT : Serotonin
-synthesized from tryptophan and stored in vesicles
trypthophan———> 5-HTP———> 5-HT
tryptophan 5-HTP
hydroxylase decarboxylase

Question 3

Acute Tryptophan Depletion

Answer 3

ATD = Reduced 5-HT

• also a procedure to reduce levels of 5HT in brain
• low protein diet for 24 hours and then invest a drink containing amino acids
• body uses amino acids to synthesize proteins which uses up available tryptophan
• reduced tryptophan = less 5-HT in brain
• associated with negative mood, can produce depressive symptoms

Question 4

Tryptophan or 5-HT Loading

Answer 4

increases 5-HT synthesis

• as nutritional supplements
• associated with more positive enhanced mood

Question 5

buspirone

Answer 5

direct 5-HT receptor agonist:

• used to reduce anxiety
• sometimes to treat depression

Question 6

SSRI antidepressants

Answer 6

inhibits 5-HT reuptake from synapse (7 currently available in the UK)
- often used to reduce levels of aggression in psychiatric conditions

Kamarck et al., (2009) in healthy people:

• reduces hostility and aggression
• increases social affiliation and co-op behavior

Question 7

Study on 5-HT receptor agonist

Answer 7

Chamberlain et al (2007)

• either: placebo, 20mg, 30mg buspirone
• drug increased contentedness in healthy individuals

Question 8

SSRIs + moral judgement

Answer 8

Crockett et al (2000)

• responses to moral dilemmas
• results: SSRI reduced acceptability of harming a person to save money

Question 9

Serotonin + memory

Answer 9

• hippocampus: crucial to memory and rich in 5-HT receptors
• ATD impairs memory performance
• impairment in: neutral and positive stimuli, memory for negative remains unaffected or even enhanced (Klaassen et al., 2002)

Question 10

Serotonin + personality

Answer 10

genetical differences in serotonergic systems could be involved in individual differences in personality
Carver & Miller (2006): serotonin relates to personality
Ilieva (2015), found that Serotonin reduced the levels of neuroticism

Question 11

Serotonin and facial processing

Answer 11

Harmer and Cowen, 2013

• acute 5-HT manipulations: affects speed and accuracy
• reducing 5-HT: impairs recognition
• increasing 5-HT: enhances recognition, without changing the mood

Question 12

Antidepressant effects of SSRIs

Answer 12

• changes in cognition (Harmer and Cowen)
• changes in social behaviour (Young et al)
  may be basis for changes in mood to occur

Question 13

Drugs and Psychotherapy?

Answer 13

• SSRIs may not affect mood directly but instead alter how brain processes stimuli
• CBT aims to teach skills for identifying dysfunctional thoughts + beliefs
• combo: may be more effective than either alone