Neurobiology of mental health Flashcards
How do you define psychosis?
“break from reality”
Positive symptoms of SCZ?
Voices, delusions, thought insertion/withdrawal/broadcast
Negative symptoms of SCZ?
Neglect, isolation, lack of emotional expression, avolition
Mesocortical Pathway
Major Pathway: ventral tegemental of the midbrain–>cortex
Result of Blocking: increase neg. symptoms of schizophrenia (i.e.social withdrawal/depression)
Mesolimbic Pathway
Major Pathway: ventral tegmental of the midbrain–>limbic system [nucleus accumbens]
Result of Blocking: relieves (+) symptoms of schizophrenia (target w/antipsychotics)
Nigrostriatal Pathway
Major Pathway: substantia nigra pars compacta–>neostriatum
Result of Blocking: Parkinson’s Disease (stimulation extrapyramidal side effects)
Tuberoinfundibular Pathway
Major Pathway: Nucleus of hypothalamus–>pituitary
Result of Blocking: increase release of prolactin from ant. pituitary (hypogonadism)
(bromocriptine–>DA agonist-tx for prolactinoma)
Name 2 drugs that work on NMDA glutamate receptors [2]
Ketamine
PCP (angel dust)
What are the changes seen on MRI in SCZ?
- Enlarged ventricles
- Reduced grey matter volumes
- Decreased gyrification=reduced ridging of white matter
- Loss of asymmetry of planum temporale (associated with auditory processing)
Outline the glutamate hypothesis in SCZ
- Reduction in glutamate release leads to direct loss of dopamine release in PFC via mesocortical pathway
- Reduction in glutamate release leads to increased positive symptoms by mesolimbic pathway – how?
lack of glutamate coming in leads to lack of dopamine coming out SO LOTS OF DOPAMINE IN MESOLIMBIC PATHWAY
What effects does dopamine have on prolactin?
Dopamine has an inhibitory effect on prolactin
Therefore, reduced dopamine by D2 antagonists causes hyperprolactinoma
What effect does too little dopamine in the nigostriatal pathway cause?
EPS
How is the limbic affected in bipolar?
Bipolar-
- underactivation of PFC and lack of regulation
+++ reduced top down regulation - reduced connectivity between amygdala and PFC
- overdrive of limbic system BOTH ways= mania + hypomania
- Amygdala becomes overactive which projects on PFC
- Decreased volume of amygdala but still overactive
- Loss of PFC and progressive hypoactivation
WHAT HAPPENS TO THE HIPPOCAMPUS IN PTSD?
Hippocampus – Involved in processing and storage of memories.
In PTSD the hippocampus shrinks (or under-develops if childhood trauma).
How is the limbic system involved in PTSD?
Sensory trigger
Hippocampus recalls fragment of memory (e.g. image)
Amygdala reacts to memory “flashback”
PFC unable to rationalise the situ. Unable to recognise person is safe
Person attempts to avoid or escape
