## 3 The Mechanisms Behind Broken MNs in ASD and Schizophrenia
### Mu Rhythm Suppression in Schizophrenia
A group of 32 participants were recruited for this study: 8 patients with active schizophrenic psychosis, 8 patients in the residual phase of the disease, and 16 controls with no reported neurological or psychiatric disorders. An EEG paradigm was administered that measured \(mu\) rhythm suppression over the sensorimotor cortex while the participants were observing their own hand movements and hand movements of other individuals. Furthermore, levels of empathy were evaluated by the implementation of the Interpersonal Reactivity Index (IRI), which involves a classification of empathy and perspective taking (Perspective Taking subscale, Empathic Concern subscale, Personal Distress subscale and Fantasy subscale). The study revealed that the levels of \(mu\) rhythm suppression in the schizophrenic patients that experience active psychotic episodes were greater over the left sensorimotor cortex, when compared to the other groups. Healthy controls and patients with schizophrenia in the residual phase exhibited no considerable differences in the levels of \(mu\) rhythm suppression. [PERSON] et al. [PERSON] et al. (2018) attributed the higher levels observed in the first group to the occurrence of psychotic episodes. In particular, the findings have shown that the more severe the psychotic symptoms, the greater the left-sided \(mu\) rhythm suppression. In addition, according to the findings from the IRI, the degree of personal distress was significantly stronger in patients with schizophrenia than controls. The outcomes of the study suggest that impaired social cognition and empathy can be attributed to abnormal function of the MNS in schizophrenic patients, and can be further negatively impacted by increased levels of distress. A study by [PERSON] et al. [PERSON] et al. (2018) has investigated the optimal dose of oxytocin (OT) for boosting the processing of social cues and contexts in patients with schizophrenia. The main aim of the study was to measure \(mu\) rhythm suppression as a proxy for the function of the MNS, and pupil dilation, which served as an index for emotion recognition and processing. The researchers recruited 47 individuals diagnosed with schizophrenia that were randomly instructed to receive one of eight doses of OT (8, 12, 24, 36, 48, 60, 72, or 84 IU), or the placebo substance. The experiment involved two tasks associated with social cues: an EEG task that measure \(mu\) rhythm suppression in reaction to biological motion, and a pupillometry task that demonstrated the level of the dilation of the pupil when observing faces that present emotion. The outcomes of the study were that OT doses of 36 and 48 IU substantially boosted \(mu\) suppression, as opposed to the placebo. Crucially, the study demonstrated no effect of the OT on the face affect pupillometry test, which can be attributed to the well-established impairment that individuals with schizophrenia present in face emotion processing and recognition [83]. Table 2 provides an overview of the studies used in this review, the methodological approach and their main findings in both conditions.