**5. Future directions**

It is possible to distinguish between two categories of factors associated with the efficacy of rTMS in schizophrenia: (1) clinical factors and (2) factors associated with rTMS, especially stimulation parameters.

Clinical factors include heterogeneity of symptoms of schizophrenia treated with rTMS, especially negative symptoms. Prikryl et al. analyzed negative symptoms influenced with rTMS using five domains of SANS (affective flattening/blunting, alogia, avolition/apathy, anhedonia, and impaired attention). The stimulation improved all domains, except for alogia [4]. To improve the results with rTMS, the definition and the prediction of responders are needed. This could be achieved using markers of impaired cortical inhibition and neuroplas‐ ticity—especially when TMS (with the potential to measure cortical inhibition and its changes) and EEG or other neuroimaging methods (MRI, fMRI, SPECT, PET) are combined. Tikka et al. described significant correlation between the reduction in negative and depressive symptoms in patients with schizophrenia and the reduction in gamma spectral power in left frontal and temporal segments after cerebellar rTMS. The authors suggest resting state gamma spectral power in frontal and temporal regions for a biomarker of treatment response [55]. Homan et al. described that responders were robustly differentiated from nonresponders to rTMS by the higher regional blood flow in the left superior temporal gyrus before treatment for AVH. The authors conclude that resting perfusion measurement before treatment might be a clinically relevant way to identify possible responders and nonresponders to rTMS [56].

The optimization of stimulation parameters is another important issue. New stimulation targets (for example, the cerebellum or anterior cingulate), better and more precise methods of stimulation coil placement (stereotactic navigation), new coil types (double cone coil, maybe H‐coils for deep TMS), stimulation frequency (individual frequency), intensity, number of pulses (higher number of pulses), and the number of stimulation sessions (intensive stimula‐ tion) are also subjects of current research. This research can provide data for new and inno‐ vative stimulation paradigms, which are needed for a more robust clinical effect of TMS in schizophrenia.
