Neuoimaging & Psychiatry Proctored Exam Complete Questions And Answers.
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Course
PSMNB
Institution
PSMNB
What is the function of the limbic system? - correct answer Integrates info from the external and internal world.
Function is to regulate and motivate behaviours, emotion regulation and recognition, biasing memory for emotionally driven salient events etc.
I...
What is the function of the limbic system? - correct answer Integrates info from the
external and internal world.
Function is to regulate and motivate behaviours, emotion regulation and recognition, biasing memory
for emotionally driven salient events etc.
Includes the hippocampus, cingulate, amygdala, septal region, and also PFC, hypothalamus, paralimbic
cortices e.g. insula, ventral striatum/accumbens and mesolimbic.
It has been shown to be closely mapped to emotional brain regions
Almost all psychiatric disorders involve dysregulation somewhere in the limbic system
Summary of depression and brain imaging - correct answer Brain volume
Cortical thinning
Subgenual cingulate
Subcortical structures (hippocampus, amygdala)
Circuit level connectivity abnormalities rather than regional abnormalities.
PET study showing differing brain volume in depression - correct answer Drevets et
al 1997 use PET to show decreased volume and decreased metabolism in subgenual cingulate in people
with depression. But small sample size.
Study (structural MRI) showing cortical thinning in depression - correct answer
Schmaal et al 2016 found using structural MRI areas where cortex was thinner in depression compared
to healthy controls were: subgenual cingulate, ventromedial PFC, cingulate, medial temporal lobe
Very small effect size but has been replicated in numerous studies so seems like a robust finding.
But don't see subgenual cingulate thinning in adolescents with depression (but there is less power
because less ppts) - perhaps is something that worsens as the disease progresses?
What is the role of the subgenual cingulate? - correct answer Not involved in
emotion. It is highly connected areas involved in emotion and is proposed (Mayberg 2003) to be
, involved in flipping activity between internal vegetative network involved in rest and recuperation and
attention to the external world.
Many studies on the Cg25 (subgenual cingulate) and depression - seems to be highly involved - correct
answer Mayberg 2003 - PET shows reminiscing on sad parts of life shows increased
glucose metabolism in Cg25
Studies have found that treating depression reduces metabolism in Cg25
Mayberg 2005 used deep brain stimulation to block Cg25 activity and depression improved.
Seems that more activity in the Cg25 is associated with depression
Study on how hippocampus is affected in depression - correct answer Schmaal et al
2016 - MRI - reduction in hippocampal VOLUME only in RECURRENT depression, not in first episode, and
moreso in EARLY ONSET. Early onset depression also had reduced volume of AMYGDALA (significance of
these two are unknown)
small effect size
Are specific parts of the hippocampus affected? - correct answer Roddy et al (2019)
- MRI - all subfields of the hippocampus are affected but as you refine it to the right you get a stronger
association between the reduced volume and depression. There also seems to be more reduction in
volume of hippocampus the MORE depressive episodes.
Hippocampus might be sensitive to depression because its an area of neurogenesis and neurogenesis is
suppressed by depression (but we don't know this)
How is the amygdala involved in depression? - correct answer Amygdala is involved
in fear processing and emotion processing more generally.
Victor et al (2010) - fMRI - shows amygdala is HYPERreactive to negative stimuli and people with
hyperactive amygdala are more likely to show response to CBT (treating negative emotional states) but
some studies according to Pandya et al (2012) suggest depression have HYPOreactive amygdalas!
Vagus nerve stimulation decreases hyperactivity of amygdala - might be useful in depression? But how it
reduces hyperactivity is still unclear.
Why are there discrepancies in the literature about areas associated with depression (e.g. is the
amygdala hyperactive or hypoactive) - correct answer Pandya et al 2012 -
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