## 3 The Mechanisms Behind Broken MNs in ASD and Schizophrenia
### Methodological Limitations and Strengths of the Included Studies
\begin{table}
\begin{tabular}{c c c c} \hline
**Authors** & **Participants** & **Method** & **Findings** \\ \hline
[59] & 46 participants & \multicolumn{3}{c}{No significant variation between ASD and controls in P3 ERP component.} \\  & 23 ASD & EEG & Larger number RP (readiness potential) Laplacian both in congruent and incongruent trials in ASD. \\  & and 23 controls & & No effect of intended action on early visual processing detected. \\ \hline
[64] & 40 participants & \multicolumn{3}{c}{When _mu_ frequency was distinguished into two sub-bands, group difference was observed in the upper sub-band (10–12/13 Hz) of the sensorimotor cortex in ASD in the condition of gestural observation; no significant variation in lower sub-band (8–10 Hz) among the two groups.} \\  & \multicolumn{3}{c}{No globally dysfunctional MN system in ASD.} \\ \hline
[62] & 40 participants & \multicolumn{3}{c}{No significant variation between ASD and controls in P3 ERP component.} \\  & 20 with-functioning autism & EEG, Eye-Tracker & \multicolumn{3}{c}{Visual attention in both groups had a significant impact on _mu_ suppression.} \\  & and 20 controls & & The _mu_ rhythm suppression of the ASD group was reduced during biological motion observation. \\ \hline
[63] & 43 participants & \multicolumn{3}{c}{Lower level of _mu_ suppression in the right hemisphere in ASD during mentalising task. Positive correlation of lower performance in mentalising task with poorer activation of mirror neurons in left hemisphere but not linked to level of autistic traits.} \\  & \multicolumn{3}{c}{EEG, Eye-Tracker, TMS-EMG} & \multicolumn{3}{c}{Assuistic traits predictive factor for _mu_ suppression in the 8–10 Hz for mentalising task and poorer mirror neuron firing in right hemisphere. During non- mentalising task, no low-level _mu_ suppression detected.} \\ \hline
[60] & 40 participants & \multicolumn{3}{c}{No significant variation among groups in _mu_ suppression occurring from EEG monitoring of observation and imitation of a gestural action. Stronger _mu_ suppression during gestural action observation than dot observation in ASD.} \\  & 20 male ASD & EEG & No imitation of the observed action while MN system activation intact in ASD. \\  & \multicolumn{3}{c}{No limitation of the observed action while MN system activation intact in ASD.} \\  & \multicolumn{3}{c}{Relation between attenuated communication capacities and reduced _mu_ rhythm.} \\ \hline
[72] & 32 outpatients with schizophrenia and 26 controls & \multicolumn{3}{c}{Linear increase in _mu_ rhythm suppression in conditions with higher social demand for both groups. Schizophrenia patients self-reported low ampatic and mentalising ability, however, the modulation of MN system functioning appeared relatively intact.} \\ \hline
[82] & 47 participants with schizophrenia & EEG & Attenuated _mu_ rhythm suppression was substantially boosted by OT doses of 36 and 48 IU. No effect of the OT on face affect pupilometry test. \\ \hline \end{tabular}
\end{table} 
Table 2: Overview of the selected research studies for this review. \begin{table}
\begin{tabular}{c c c c} \hline
**Authors** & **Participants** & **Method** & **Findings** \\ \hline \multirow{6}{*}{[81]} & 32 participants with schizophrenia: & & \\  & 8 actively psychotic & & \\  & 8 activity & psychotic & \\  & 8 patients, 9 patients in & EEG & \\  & the residual phase of & & \\  & illness, 6 healthy & & \\  & controls & & \\ \hline \multirow{6}{*}{[73]} & 15 drug-naive or & & \\  & drug-free patients & & \\  & with schizophrenia & EEG & \\  & and 15 healthy & & \\  & controls & & \\ \hline \multirow{6}{*}{[76]} & Studies involving & & \\  & schizophrenia & & \\  & patients with active & & \\  & negative symptoms, & & \\  & high-functioning & & \\  & ASD participants and & & \\  & healthy controls & & \\ \hline \end{tabular}
\end{table} 
Table 2: Cont.