Does Prefrontal Noninvasive Brain Stimulation Alleviating Symptoms in Depression and Schizophrenia Impact Mood and Emotion Processing?
Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are noninvasive brain stimulation techniques currently used as therapeutic tools in various psychiatric conditions. Applied over the dorsolateral prefrontal cortex (DLPFC), they showed their efficacy in reducing drug-resistant symptoms in patients with major depression and in patients with schizophrenia with predominantly negative symptoms. The DLPFC is a brain structure involved in the expression of these symptoms as well as in other dysfunctional functions observed in theses conditions such as emotional processes. The goal of this review is to establish whether or not a link exists between clinical improvements and modulation of emotional processes following the stimulation of the DLPFC in both conditions. The data collected show that improved emotional processes is not linked to a clinical improvement neither in patients with depression nor in patients with negative schizophrenia. Our results suggests that although sharing common brain structures, the brain networks involved in both symptoms and in emotional processes would be separate.