Article 3: fMRI of inner speech in sz Flashcards
What was the main hypothesis?
Reduced auditory cortex activity in controls but not in people with SZ
Describe two pieces of evidence supporting this hypothesis.
Other studies showed this effect
Based on the idea that thee is faulty efference copy mechanism
Auditory cortex active during hallucinations
what was the second hypothesis?
People with SZ have disrupted self monitoring that leads them to mistake inner speech for external speech, leading to hallucinations.
SZ would show decreased suppression of auditory regions during inner speech compared to CTLs
What were the pieces of evidence for the “H: People with SZ have disrupted self monitoring that leads them to mistake inner speech for external speech, leading to hallucinations.
SZ would show decreased suppression of auditory regions during inner speech compared to CTLs?”
Auditory regions are active during hallucinations
Similar activity in auditory regions for hallucinations and external sounds (Dierks in Lecture 10)
Auditory regions active during inner speech in healthy controls
SZ showed greater activity in auditory regions when imagining someone else speaking
Why is activity in auditory cortex decreased during inner speech?
When we speak, motor cortex lets auditory cortex know (corollary discharge or efference copy)
This reduces activity in auditory cortex
This lets us know that we are speaking, not someone else
This also happens when we just imagine speaking (inner speech or talking to ourselves)
During inner speech, the cingulate cortex is becomes more active
Likely due to its role in action monitoring
participants
15 M SZ and 12 CTLs
Right-handed
Patients and the ctls were matched for age, sex and handedness and all spoke English
All SZ experienced auditory hallucinations
All on medication
No recreational drugs
task
Stimuli: 24 neutral sentences, spoken by a adult female native English speaker
Two part trial:
Listen + Inner Speech (repeat silently) + press button when done
Listen + Listen
Baseline: silence
Comparisons:
Second half of the trial when people were either listening or repeating silently
Results (Behavioural)
No significant differences between SZ and controls
Listening: Greater activity in auditory and parietal
Inner speech: Greater activity in inferior frontal and cingulate
Listening - Inner speech > Silence
Larger differences for SZ in parietal and cingulate
Larger differences for CTL in auditory
What do the results tell us about possible mechanisms underlying hallucination in SZ?
SZ patients show reduced auditory suppression during inner speech»_space; Evidence of a defective self-monitoring system.
SZ patients show reduced engagement of the Cingulate (ACC) during inner speech. ACC is involved in self-monitoring of action »_space; related to misattributions of inner speech as external (i.e., hallucinations)
