Scientists have uncovered differences in the brains of people with schizophrenia who do and do not have hallucinations.
Dr Jon Simons and colleagues at Cambridge University, UK, looked at 153 structural Magnetic Resonance Imaging scans of people with schizophrenia and similar healthy individuals.
The team measured the length of the paracingulate sulcus – a fold towards the front of the brain – in each scan. This indicated a link between length of the paracingulate sulcus and a tendency to hallucinate.
Analysis suggests that a 1cm reduction in the fold’s length was linked to a 20% rise in the chance of hallucinations. The association applied to both auditory and visual hallucinations. The team say this is consistent with an explanation based on "reality monitoring". The paracingulate sulcus is thought to play a role in distinguishing self-generated information from that perceived in the outside world.
Details were published yesterday (17 November) in the journal Nature Communications.
In scans of healthy people, Dr Simons has previously found that variation in the length of the paracingulate sulcus was linked to reality monitoring. He says: "Schizophrenia is a complex spectrum of conditions that is associated with many differences throughout the brain, so it can be difficult to make specific links between brain areas and the symptoms that are often observed.
"By comparing brain structure in a large number of people diagnosed with schizophrenia with and without the experience of hallucinations, we have been able to identify a particular brain region that seems to be associated with a key symptom of the disorder."
Changes in other areas of the brain are also likely to be important in generating the complex phenomena of hallucinations, the team adds.
Garrison, J. R. et al. Paracingulate sulcus morphology is associated with hallucinations in the human brain. Nature Communications 17 November 2015 doi: 10.1038/NCOMMS9956 [abstract]
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