SZ, Myelination and Delayed Corollary Discharge (Whitford et al 2010) Flashcards
Why does the age of onset of SZ support the theory of demyelination?
Could be abnormal myelination of white matter fasciculi in the frontal lobe
This develops last in adolescence/early 20s
What is white matter CNS mostly made of?
Oligodendrocytes
How does myelin work?
Covers the oligodendrocytes in the white matter to act as electrical stimulation
This keeps signal amplitude and conduction velocity high
The problem in SZ lies in the brain regions
T/F
F
The connections between the brain regions are the problem
Andreasen
Primary sensorimotor fasciculi are not affected by abnormal myelination
T/F
T
No motor symptoms in SZ
Which circuit does the cingulum work in that is associated with abnormal functioning in SZ?
Papez circuit
Responsible for emotion, memory, aversion, gratification
What connects Broca’s and Wernicke’s area
Arcuate
Which specific myelin abnormalities are seen in SZ?
Less oligodendrocytes
Irregular myelin microstructure
Subnormal expression of myelin genes
How did Blakemore determine that the abnormal corollary discharge lead to altered perception?
Blakemore et al
Either got a robot to tickle a person on button press or a subsecond after
Should find the one on the button press less ticklish
This doesn’t happen in SZ
Hypothesised its because the corollary discharges arrive to early to perceive the stimulus properly
Which type of events are least salient?
Self-generated as the corollary discharge mechanism should predict the outcome
Why do normally non-salient events become salient in SZ?
Discrepancy between predicted feedback and actual feedback
Due to abnormal corollary feedback
Why may depression occur in SZ?
Abnormal DA system takes over from the normal DA system and then normally rewarding stimuli are not perceived as pleasurable
How may prediction error lead to change in DA firing?
Increases it in midbrain - Voss et al
Decrease in neuron firing - Schultz et al
Why don’t the neurons just adapt?
The myelin abnormalities may change over time
Like in MS
This fits with a fluctuating clinical picture of SZ
Why is it likely that myelin disruption increases DA?
Blockage of neuroregulin-1 by Roy et al blocks oligodendrocyte development
Shows increase in DA receptors and transporters
