## 3 The Mechanisms Behind Broken MNs in ASD and Schizophrenia  
### Mu Rhythm Suppression in ASD  
Attenuations in the function of the MNS in autism have been included in the theory of \"broken mirror neurons\", which has been researched over recent decades to explore possible links between atypical MN functionality and ASD symptomatology. Cognitive deficits in individuals with autism, and impairments in communication and social integration may be traced back to these links [53]. Dysfunctions in MNs have received attention in the field of autism research; nevertheless, they have also received criticism, mostly due to the mixed findings. It has been claimed that deficits in the sensorimotor system in individuals with ASD is a more plausible reasoning for explaining problems in mentalizing, imitation,and action interpretation. In addition, it has been proposed that the activation of MNS is fundamental for social cognition and reasoning [54; 55] as well as the understanding of mental and emotional states [56]. These abilities have been well researched in ASD, which is often characterized by considerable discrepancies in internal state reasoning and Theory of Mind [57]. Measurements of suppression of the \(mu\) wave EEG have been prominent in exploring MN function in individuals. In clinical populations, however, and in ASD in particular, \(mu\) rhythm suppression has not been the most effective method. This may be attributed to various reasons ranging from sample sizes to issues with electrode selection for data collection. Neuroimaging studies provide insights into abnormalities in ASD in cerebral areas that are crucially implicated in social cognition and processing of social stimuli, for instance, the prefrontal cortex and the superior temporal sulcus [50]. One of the most prominent components that is hypothesised to trigger the activation of MNs is the observation of an action. Action observation involves, among others, the processing of facial expressions further related to ToM skills and emotion recognition [58]. [PERSON] et al. [59] critically examined the motor interference effect in ASD, which corresponds to more errors and slower reaction times when an individual visually perceives a movement that contradicts the movement of intention. A group of 23 adults with high-functioning autism and 23 age-, handedness- and sex-matched healthy controls participated in an EEG paradigm. The study focused on the P3 (a positive deflection in EEG recordings that occurs approximately 300 ms after stimulus onset, and is associated with attention and stimulus evaluation), the N190 (a negative ERP component occurring around 190 ms after stimulus onset, commonly linked to early visual processing and face recognition), and the RP (\"Readiness Potential\", a slow negative shift in EEG activity preceding voluntary movement, indicating motor preparation) that were congruent to the conditions of the stimulus. The participants were instructed to visually follow the gestural movements of a videotaped hand. Directly after the end of the observation, the participants were instructed to perform a pre-instructed gesture. The experiment involved a congruent condition, under which the required action matched the shown hand movement; an incongruent condition, where the observed gesture did not match the one for execution; and a baseline condition (hand in resting state). The aim of the study was to examine whether impairments in the processing of self- and other-action performances could provide a justification for imitation attenuations in high-functioning ASD. The results demonstrated that, in contrast with the predictions of the researchers of the study, there was no reported difference between the high-functioning autistic group and the control group in the P3 ERP component. In particular, both groups presented larger numbers of the P3 component when observing the congruent hand movement condition, so distinguishing between congruent and incongruent hand movements with high processing levels was intact.