Dopamine, Salience & Schizophrenia (Lect 3)

Question 1

Monoamine neurotransmitters

Answer 1

• synthesized from dietary amino acids (high protein level foods: meat, eggs etc.)
• DA + NA: are catecholamines, derived from the amino acid tyrosine
• serotonin is derived from tryptophan

Question 2

The brains dopaminergic systems

Answer 2

1. Dorsal (upper) pathway: nigrostriatal system
   from substantial migration to basal ganglia + striatum
   2.Ventral (lower) pathway: mesolimbocortical system
   From ventral tegmental area of brain stem to basal forebrain + prefrontal cortex

Question 3

dopamine in reward and addiction

Answer 3

addictive drugs hijack the reward system
some drugs (e.g. cocaine) rapidly increase DA levels through the brain

Question 4

Schizophrenia

Answer 4

“Split-mind”

• splitting off, dis-integration of mental functions
• disconnection between subjective experience and reality

Question 5

Positive / florid symptoms of Schizophrenia

Answer 5

+ presence of abnormality
+ disordered thought and speech, hallucinations, delusions
+ linked to increased levels of DA

Question 6

Negative / deficit symptoms of Schizophrenia

Answer 6

• absence of normality
• lach of emotion, apathy, inability to feel pleasure, social withdrawal
• linked to reduced levels of DA^^

Question 7

Drugs that increased DA levels

Answer 7

• L-Dopa
• amphetamine
• cocaine

Question 8

Drugs that decrease DA levels

Answer 8

• anti-psychotics

can cause parkinson’s like side effects

Question 9

The Salience hypothesis

Answer 9

By Kapur, 2003

• a neurocognitive explanation for link between dopamine and psychosis
• normally people have an accurate salient stimulus or event is signaled by dopamine release in basal forebrain area
• in psychotic patients this process is disrupted…. increased DA levels coincide with events + stimulus with no significiance

Question 10

Kapur (2004) on antipsychotics

Answer 10

• neuroleptic drugs are effective in treating symptoms of Schiz. Bly blocking dopamine receptors and reducing inappropriate experiences of salience
• side effects: can include feelings of salience/motivation and worsening of neg- symptoms
• neuroleptic induced dysphoria

Question 11

Neurodevelopmental model of Psychosis

Answer 11

Murray et al. (2008)

• early age: effects of genes, pre-natal infections, subtle motor problems, cognition and social functioning
• Environmental influences: effects of chronic social adversity (stress isolation etc)
• teenagers: social anxiety, depression, paranoia

can lead to dopamine dysregulation => psychosis