Less volume than normal this month, but some interesting papers nonetheless, including:
- How does hallucinating a voice differ to imagining a voice (an fRMI study)?
- How do voices and visions co-occur in daily life, and relate to emotional fluctuations?
- How does the resting brain of people with and without hallucinations differ?
- Is TMS effective for children who hallucinate?
- Plus some other bonus papers.
Accessible summary: What’s the difference between hallucinating a voice, and simply imagining a voice? This study compared the brain activation when people were hearing voices (i.e., having auditory hallucinations) in the scanner, to the brain activation when the same people then imagined hearing the voice they had just heard. The study found that a specific area of the brain, the supplementary motor area (SMA) was activated more strongly when people were imagining hearing a voice, as compared to when they were hallucinating. The theory runs that this SMA region of the brain is involved in telling us if ‘we’ have produced a thought, and that in the case of hallucinations, it doesn’t activate enough. As such we don’t think we have created the thought, and experience it as a hallucination.
Link to paper: http://dx.doi.org/10.1016/j.nicl.2012.09.007
Accessible summary: This study used the Experience Sampling Method (ESM) to study hallucinations. This works by the person carrying a phone/watch with them that beeps at random times during the day, and when it does the person records what they are thinking/feeling/experiencing, in relation to specific questions that pop up on the phone/watch. Firstly, the study found that whereas visions were typically accompanied by voices, voices regularly occurred without visions. Higher levels of emotion did not precede hallucination onset, leading the researchers to argue that “affective dysregulation” might not play a primary role in hallucination onset.
Link to paper: http://dx.doi.org/10.1016/j.schres.2012.06.010
Accessible summary: This study compared the brains of people who hallucinated with the brains of people who do not hallucinate, when they were simply doing nothing (i.e., were ‘at rest’). The aim was to see what factors, if any, in the resting brain acted as vulnerability factors for hallucinations. First they found that ‘hallucinators’, compared to controls, had a right parahippocampal gyrus (involved in memory) that was more chatty with (i.e., more strongly connected to) their right inferior frontal gyrus (involved in aspects of speech production), but that their right inferior frontal gyrus was less chatty with their right dorsolateral prefrontal cortex (involved in memory). Furthermore, ‘hallucinators’ left superior temporal gyrus (involved in speech perception) was less chatty with their left hippocampus (involved in memory) compared to controls. The authors conclude that key regions of the brains involved in speech production and perception have altered connections to memory retrieval areas of the brain in people who hallucinate compared to people who do not hallucinate.
Link to paper: http://dx.doi.org/10.1371/journal.pone.0043516
Accessible summary: This study treated 10 children/young adults (mean age 15 years of age), diagnosed with childhood onset schizophrenia with hallucinations, using TMS. The 10 children in the trial had not responded to two consecutive 8-week regimens
of antipsychotics. The theory was that TMS could help avoid the “adverse developmental consequences of polypharmacy” (i.e., the negative effects of using loads of pharmaceutical drugs). TMS was applied over the left temporoparietel junction (where the temporal and parietal lobes meet in the left hemisphere of the brain) for 5 consecutive days. TMS involves the painless application of a changing magnetic field over a specific part of the brain, which causes an electrical field in that part of the brain, and leads to neural changes. It was found that hallucination severity reduced in the children at the end of TMS treatment.
Link to paper: http://dx.doi.org/10.1016/j.jaac.2012.06.010
There are also a couple of other papers published this month, that I won’t attempt to summarise, but will mention:
- Homans et al. Auditory verbal hallucinations: imaging, analysis, and intervention. http://www.ncbi.nlm.nih.gov/pubmed/22940743
- Svetel et al. Hallucinations in Parkinson’s disease: Cross-sectional study. http://www.ncbi.nlm.nih.gov/pubmed/22427287
- Bartels-Velthuis et al. Consistency and reliability of the auditory vocal hallucination rating scale (AVHRS). http://dx.doi.org/10.1017/S2045796012000108
That’s all for this month in voices. See you next month.