Transcranial magnetic stimulation of Wernicke's and Right homologous sites to curtail "voices": a randomized trial

The role of the superior temporal lobe in auditory false perceptions: a transcranial direct current stimulation study

Neuroimaging has shown that a network of cortical areas, which includes the superior temporal gyrus, is active during auditory verbal hallucinations (AVHs). In the present study, healthy, non-hallucinating participants (N=30) completed an auditory signal detection task, in which participants were required to detect a voice in short bursts of white noise, with the variable of interest being the rate of false auditory verbal perceptions. This paradigm was coupled with transcranial direct current stimulation, a noninvasive brain stimulation technique, to test the involvement of the left posterior superior temporal gyrus in the creation of auditory false perceptions. The results showed that increasing the levels of excitability in this region led to a higher rate of ‘false alarm’ responses than when levels of excitability were decreased, with false alarm responses under a sham stimulation condition lying at a mid-point between anodal and cathodal stimulation conditions. There were also corresponding changes in signal detection parameters. These results are discussed in terms of prominent cognitive neuroscientific theories of AVHs, and potential future directions for research are outlined.

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Investigated role of left STG in false perceptions of voices in white noise.

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Used noninvasive brain stimulation whilst participants listened to white noise.

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Tested whether number of false perceptions was affected by stimulation of STG.

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Higher false alarm rate when excitability increased than when decreased.

Review of the efficacy of transcranial magnetic stimulation for auditory verbal hallucinations

With an increase of the number of studies exploring repetitive transcranial magnetic stimulation (rTMS) for the treatment of auditory verbal hallucinations (AVH), an update is provided on the efficacy of different paradigms. A literature search was performed from 1966 through April 2013. Twenty-five randomized controlled trials using the severity of AVH or psychosis as outcome measures were included. Standardized mean weighted effect sizes were computed; a qualitative review of the literature was performed to assess the effects of various rTMS paradigms. rTMS versus sham treatment for AVH yielded a mean weighted effect size of .44. No significant mean weighted effect size was found for the severity of psychosis (i.e., .21). For patients with medication-resistant AVH, the mean weighted effect size was .45. rTMS applied at the left temporoparietal area with a frequency of 1 Hz yielded a moderate mean weighted effect size of .63, indicating superiority of this paradigm. Various other paradigms failed to show superior effects. rTMS applied at the right temporoparietal area was not superior to sham treatment. rTMS, especially when applied at the left temporoparietal area with a frequency of 1 Hz, is effective for the treatment of AVH, including in patients with medication-resistant AVH. The results for other rTMS paradigms are disappointing thus far. A next step should be to explore the effects of rTMS in medication-free individuals, for example, during the initial phases of psychosis, and in patients with diagnoses other than schizophrenia who do not have comorbid psychotic symptoms.

Auditory verbal hallucinations as atypical inner speech monitoring, and the potential of neurostimulation as a treatment option

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We discuss ‘inner speech’ theories of auditory verbal hallucinations.

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Atypical self-monitoring may lead to the experience of inner speech as external.

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We summarize research into the use of neurostimulation to treat hallucinations.

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Effects of neurostimulation may be due to modulation of self-monitoring networks.

Auditory verbal hallucinations (AVHs) are the experience of hearing voices in the absence of any speaker, often associated with a schizophrenia diagnosis. Prominent cognitive models of AVHs suggest they may be the result of inner speech being misattributed to an external or non-self source, due to atypical self- or reality monitoring. These arguments are supported by studies showing that people experiencing AVHs often show an externalising bias during monitoring tasks, and neuroimaging evidence which implicates superior temporal brain regions, both during AVHs and during tasks that measure verbal self-monitoring performance. Recently, efficacy of noninvasive neurostimulation techniques as a treatment option for AVHs has been tested. Meta-analyses show a moderate effect size in reduction of AVH frequency, but there has been little attempt to explain the therapeutic effect of neurostimulation in relation to existing cognitive models. This article reviews inner speech models of AVHs, and argues that a possible explanation for reduction in frequency following treatment may be modulation of activity in the brain regions involving the monitoring of inner speech.