Effect of Low-Frequency rTMS on Electromagnetic Tomography (LORETA) and Regional Brain Metabolism (PET) in Schizophrenia Patients with Auditory Hallucinations

Abstract

Background: Auditory hallucinations are characteristic symptoms of schizophrenia with high clinical importance. It was repeatedly reported that low frequency (≤1Hz) repetitive transcranial magnetic stimulation (rTMS) diminishes treatment-resistant auditory hallucinations. A neuroimaging study elucidating the effect of rTMS in auditory hallucinations has yet to be published. Objective: To evaluate the distribution of neuronal electrical activity and the brain metabolism changes after low-frequency rTMS in patients with auditory hallucinations. Methods: Low-frequency rTMS (0.9 Hz, 100% of motor threshold, 20 min) applied to the left temporoparietal cortex was used for 10 days in the treatment of medication-resistant auditory hallucinations in schizophrenia (n = 12). The effect of rTMS on the low-resolution brain electromagnetic tomography (LORETA) and brain metabolism (¹⁸FDG PET) was measured before and after 2 weeks of treatment. Results: We found a significant improvement in the total and positive symptoms (PANSS), and on the hallucination scales (HCS, AHRS). The rTMS decreased the brain metabolism in the left superior temporal gyrus and in interconnected regions, and effected increases in the contralateral cortex and in the frontal lobes. We detected a decrease in current densities (LORETA) for the beta-1 and beta-3 bands in the left temporal lobe whereas an increase was found for beta-2 band contralaterally. Conclusion: Our findings implicate that the effect is connected with decreased metabolism in the cortex underlying the rTMS site, while facilitation of metabolism is propagated by transcallosal and intrahemispheric connections. The LORETA indicates that the neuroplastic changes affect the functional laterality and provide the substrate for a metabolic effect.

LORETA Functional Imaging in Antipsychotic-Naive and Olanzapine-, Clozapine- and Risperidone-Treated Patients with Schizophrenia

“…The omnibus null hypothesis of no activation anywhere in the brain was rejected if at least 1 t value (i.e. voxel, t MAX ) was above the critical threshold for p = 0.05, determined by 5,000 randomizations [16] .…”

Psilocybin-induced spiritual experiences and insightfulness are associated with synchronization of neuronal oscillations

“…The LORETA inverse solution is based on the assumption that synchronized discharge is required for generating cortical EEG rhythms, an assumption that has been consolidated in numerous intracerebral studies (Buzsáki et al 2012). LORETA has been applied in almost thousand peerreview publication (Thatcher et al 2012) and has received considerable cross-modal validation from several studies combining LORETA with more established localizing methods such as functional MRI (Vitacco et al 2002;Mulert et al 2004;Mulert et al 2005;Olbrich et al 2009;Neuner et al 2014), structural MRI (Worrell et al 2000;Babiloni et al 2011;Babiloni et al 2013;Vecchio et al, 2015), diffusion spectrum magnetic resonance imaging (Thatcher et al 2012), or positron emission tomography (Pizzagalli et al 2004;Horacek et al 2007). We apply eLORETA, which has no localization bias even in the presence of structured noise ) and, therefore, was found to have a slightly increase localization performance compared to the previous version, called sLORETA (Jatoi et al 2014).…”

Placebo Response in Repetitive Transcranial Magnetic Stimulation Trials of Treatment of Auditory Hallucinations in Schizophrenia: A Meta-Analysis

“…7 Then, in contrast, another study reported a much larger effect size of 1.04 for 1 Hz rTMS in patients with AVH. 8 This study included 2 open-label trials in which the clinical evaluators were aware of the treatment delivered to each patient and for which the large positive effects 9,10 could bias the results and may explain the difference. Slotema et al produced 2 meta-analyses with effect sizes of 0.54 11 and 0.44.…”