Hallucinations linked to differences in brain structure
News Nov 17, 2015
People diagnosed with schizophrenia who are prone to hallucinations are likely to have structural differences in a key region of the brain compared to both healthy individuals and people diagnosed with schizophrenia who do not hallucinate, according to new research.
The study, led by the University of Cambridge in collaboration with Durham University, Macquarie University, and Trinity College Dublin, found that reductions in the length of the paracingulate sulcus (PCS), a fold towards the front of the brain, were associated with increased risk of hallucinations in people diagnosed with schizophrenia.
The PCS is one of the last structural folds to develop in the brain before birth, and varies in size between individuals. In a previous study, a team of researchers led by Dr Jon Simons from the Department of Psychology at the University of Cambridge, found that variation in the length of the PCS in healthy individuals was linked to the ability to distinguish real from imagined information, a process known as ‘reality monitoring’.
In this new study, published in the journal Nature Communications, Dr. Simons and his colleagues analyzed 153 structural MRI scans of people diagnosed with schizophrenia and matched control participants, measuring the length of the PCS in each participant’s brain. As difficulty distinguishing self-generated information from that perceived in the outside world may be responsible for many kinds of hallucinations, the researchers wanted to assess whether there was a link between length of the PCS and propensity to hallucinate.
The researchers found that in people diagnosed with schizophrenia, a 1 cm reduction in the fold’s length increased the likelihood of hallucinations by nearly 20%. The effect was observed regardless of whether hallucinations were auditory or visual in nature, consistent with a reality monitoring explanation.
“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,” says Dr Simons. “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.”
The researchers believe that changes in other areas of the brain are likely also important in generating the complex phenomena of hallucinations, possibly including regions that process visual and auditory perceptual information. In people who experience hallucinations, these areas may produce altered perceptions which, due to differences in reality monitoring processes supported by regions around the PCS, may be misattributed as being real. For example, a person may vividly imagine a voice but judge that it arises from the outside world, experiencing the voice as a hallucination.
“We think that the PCS is involved in brain networks that help us recognize information that has been generated ourselves,” adds Dr Jane Garrison, first author of the study, “People with a shorter PCS seem less able to distinguish the origin of such information, and appear more likely to experience it as having been generated externally.
“Hallucinations are very complex phenomena that are a hallmark of mental illness and, in different forms, are also quite common across the general population. There is likely to be more than one explanation for why they arise, but this finding seems to help explain why some people experience things that are not actually real.”
Note: Material may have been edited for length and content. For further information, please contact the cited source.
Garrison JR et al. Paracingulate sulcus morphology is associated with hallucinations in the human brain. Nature Communications, Published November 17 2015. doi: 10.1038/ncomms9956
Dissociation of Puberty and Adolescent Social DevelopmentNews
Researchers find coming-of-age is independent of puberty.READ MORE
Nociceptive Interneurons Control Modular Motor Pathways to Promote Escape BehaviorNews
Scientists locate nerve cells that enable fruit flies to escape danger.READ MORE
Exposure to Low Levels of BPA during Pregnancy Can Lead to Altered Brain DevelopmentNews
New research in mice provides an explanation for how exposure to the widely used chemical bisphenol A (BPA) during pregnancy, even at levels lower than the regulated “safe” human exposure level, can lead to altered brain development and behavior later in life.READ MORE
Comments | 0 ADD COMMENT
World Congress on Pathology and Laboratory Medicine
Sep 10 - Sep 11, 2018
World Congress on Advances in Addiction Science and Medicine
Sep 24 - Sep 25, 2018