Article 2: White matter Connectivity in the mirror neuron system Flashcards
Why did the researchers hypothesize that there would be differences in the white matter connections of the mirror neuron system in SZ? What evidence did they give to support their hypothesis?
1) People with SZ have deficits in social cognition
2) Social cognition is linked to the mirror neuron system (MNS)
3) People with SZ have functional changes in the mirror neuron system
4) Reduced MNS activity was related to greater severity
5) One previous study showing reduced white matter (WM) connections in part of the MNS
6) SZ is a disconnection disorder, so the reduced MNS function and poor social cognition might be related to impaired WM connections in that system.
SZ compared to controls when performing social cognition tasks (Sally-Anne task). What were the findings?
Reduced activity in the mirror neuron system
Reduced mirror neuron activity related to:
Poorer performance on social cognition
More negative symptoms (Impoverished emotional expression, reduced sociality, poor motivation)
Define the Mirror neuron system
Active when watching others’ actions
Important for social cognition
- Imagining (mirroring) what someone else is doing or feeling
- Active during theory of mind tasks (Sally-Anne task)
What were their aims/hypotheses?
Assess WM connections in the MNS system
See if was related to negative symptoms that are related to social cognition:
Anhedonia/Asociality
- Ability to feel closeness and intimacy
- Relationship with friends and peers
Who were the patients?
Ist episode
Why Ist episode?
They were comparing Chronic vs newly diagnosed
to see any differences that might be related to development of SZ
Variability in medications more common in _______
1st episode
Which connections between which regions of the mirror neuron system were measured?
Connections btw PMC and IPL; btw PMC and ACC; IPL and ACC
What were the different measures and what do they tell us about white matter structure?
FA= individual fibre integrity, myelination Trace = water content in the bundle (spread) space in between
Which associations did they also look at?
Inferior parietal sulcus → premotor cortex
Premotor cortex → anterior cingulate
What were their findings?
FA: higher values = ↑ directionality = ↑ myelination, ↑ fibers
Trace: higher values = greater diffusion = ↓ myelination, ↓ fibers
What were the clinical symptom measures used? Why were these measures thought to be related to possible differences in connectivity ?
1) SANS – scale for negative symptoms in SZ
- Asociality and anhedonia
[Relationships with friends
Ability to feel closeness and intimacy]
2) MNS related to theory of mind. These symptoms related to theory of mind.
3) SAPS – scale for positive symptoms in SZ
Which connections in the mirror neuron system showed differences? What were those differences? What clinical measures where they related to? What do these findings tell us?
- SZ had overall higher Trace (not good) in connections from IPL to PMC and PMC to ACC
- Greater trace in left IPL-PMC was associated with intimacy&closeness
- Greater trace in left PMC-ACC was associated with friend&peers
SZ had overall _______ in connections from IPL to PMC and PMC to ACC
higher Trace (not good)
