Neurobiology of mood disorders

Question 1

Functional differentiation in the brain:

name the 2 systems?

Answer 1

Appetitive/approach

Aversive/defensive

Question 2

Appetitive/approach systems:

• function?
• what NT is involved?
• what parts of the brain are involved? (5)

Answer 2

• to mediate seeking and approach behaviours
• dopamine- mesolimbic, cortical projection

-ventral striatum
dorsal striatum
amygdala
anterior cingulate 
orbitofrontal cortex

Question 3

Aversive/defensive systems:

• function?
• what NT is involved?
• what parts of the brain are involved? (4)

Answer 3

• to promote survival in the event of threat
• serotonin

-Central nucleus of amygdala
hippocampus
ventroanterior and medial hypothalamus
periaqueductal gray matter

Question 4

Disordered appetitive functioning

• the following biological changes lead to what symptoms in depression?
  1. difficulty identifying rewarding stimuli
  2. reduced contact with prev rewarding stimuli
  3. increased contact with aversive stimuli
  4. overall reduction in behaviour
  5. move less, eat less, lose weight, less sex
• the following biological changes lead to what symptoms in mania/hypomania?
  1. previously neutral stimuli become “rewarding”
  2. increased exploration /overall activity
  3. increased “appetite” for food, activity, sex
  4. intolerant of “aversion” / boredom
  5. intolerant of frustration
  6. elevated / elated mood??

Answer 4

• 1.attention/concentration probs
  2. loss of interest
  3. /4. avoidance
  5. inactivity, anhedonia, weight change, loss of libido
• 1.increased interest/distractability
  2. overactive/loss of need for sleep
  3. /4.disinhibition, risk taking, poor judgement
  5. /6. irritability/dysphoria

Question 5

Depression

• genetics?
• What endocrine changes occur in major depression (relating to HPA axis & HPT axis)?

Answer 5

-increased risk if family hx of severe depression
link with the short form of the 5-HTT gene

-HPA axis- cortisol
inc secretion of ACTH & CORT
inc CRH in CSF with blunted ACTH to CRH
enlarged adrenal glands 
fail to suppress cortisol on dexamethasone suppression test 

HPT axis- T3 & T4
increased TRH is CSF
TSH response to TRH blunted

Question 6

effects of stress on hippocampal neurones?

Answer 6

dendritic tree reduced so there are less branches

Question 7

What are the main areas of the brian implicated in mood disorders?

Answer 7

orbital and prefrontal cortex & ventromedial prefrontal cortex
Dorsolateral prefrontal cortex
hippocampus and amygdala
anterior cingulate cortex

Question 8

What happens to hippocampus with depressive episodes?

Answer 8

reduces hippocampal volume so impaired memory function

Question 9

Function of the anterior insular cortex

Answer 9

visceral sensory region
connects with the ant cingulate cortex
get co-activation of AIC and ACC during almost all studies of emotion

Question 10

Brain changes in bipolar disorder?

Answer 10

reduced grey matter volume in ant cingulate
inc metabolism in the amygdala
reduced glial cells