Neuroanatomical Models of Affective Disorders

Question 1

What are some of the agreed principles regarding neuronal activity and affective disorders?

Answer 1

That is effected by networks

those networks relate to the frontal and subcortical regions

BUT:
How they are disrupted is unclear

The DMN is related to self, but also others

Question 2

What are some of the critiques of neuroanatomical models of affective disorder?

Answer 2

1: Relationship between symptoms and components is unclear
2: Relationship between structures and function based on poorly tested hypothesis- Frontal inhibition
3: Structures and functions appear across disorders-OCD, Depression, Panic
4: Difference between mood states and trait vulnerability not modelled well.

Question 3

How does the BOLD signal work?

Answer 3

Blood Oxygen Level Dependent effect

Uses electrode to measure field potentials in local area, recording summation of neurons firing.

Used to show relationship between Specific cognitive function and anatomical representation.

BUT: relative only to baseline

Question 4

What are the limitations and solutions to BOLD fMRI?

Answer 4

1:The stimuli used is interpreted subjectively:

Control for subjective experience by obtaining ratings as covariants

Choose stimuli that mitigates subjective experience.

2:Whole Brain illusion: Signals drop out near air filled cavities and bones

Look at images to determine drop out and use optimised sequences.

3: Multiple comparisons across many voxels decreases power

Have a hypothesis and defined region

4: fMRI shows activation in regions not necceasry

legion or virtual legion (Transcanial Magnetic Stimulation) or neurofeedback to confirm causal role

5: Lots of repetitions to get valid signal 2% only is BOLD

Less experiments in session

6: Bold has several seconds delay

Use of MEG, EEG, fMRI/EEF if time matters

7: Same regions activated for differing tasks and stimuli

Beware of reverse inference

Question 5

What has Meta-analysis in 2012 shown regarding MDD and controls regarding brain morphology and function?

Answer 5

1: Decrease in grey matter volume in MF areas
2: Ventral striatum abnormalities
3: Sub general metabolism (PET)

Question 6

Why was it useful to use Schizophrenia patients as a control?

Answer 6

Control for antidepressants

Comparable stress levels

Question 7

What did a meta-analyis find regarding the amygdala in Bipolar and schizophrenic patients?

Answer 7

Amygdala size was effected by:

Mood stabilisers
Antidepressants
Antipsychotics
When study was published

Shows importance for controls in Meta-analysis

Question 8

What are some of the issues with Cross-Sectional designs?

Answer 8

Healthy vs Symptomatic controls

Medication
Distress
motivation to participate
Mood state not controlled for

Question 9

What are the pros and cons of Longitudinal Studies?

Answer 9

Discern correlates of symptoms and vulnerability

Imaging can show effects of medication

However:

Harder and more expensive

Question 10

What are the general problems with Affective disorder research?

Answer 10

Co-morbitity

Small sample sizes