Table 2.

Overview of results from TMS-EMG studies^*

Measure	Main findings	Hypothesis
Resting motor threshold	Fifteen studies reported no significant differences between medicated patients with chronic schizophrenia and healthy controls;54,60,78–90 1 study91 reported no significant difference between medication-naive or minimally treated (< 1 month) patients with first-episode psychosis and healthy controls; 1 study reported lower RMT in medicated patients;92 2 studies reported higher RMT in medicated patients with chronic schizophrenia;93,94 1 study showed higher RMT in medicated patients45	Patients would show deficits in GABA-mediated cortical inhibition as measured by CSP and paired-pulse inhibition paradigms (e.g., SICI and LICI). Intracortical facilitation may not be significantly different between patients and healthy controls
Active motor threshold	Two studies reported no significant differences between patients with chronic schizophrenia (mostly medicated) and healthy controls84,86 or healthy siblings86
Amplitude of motor evoked potentials	Four studies found no significant differences between medicated and unmedicated patients with chronic schizophrenia and healthy controls;81,82,87,94 2 studies reported unaltered MEP sizes in medicated patients with first-episode schizophrenia58 and medicated patients;89 1 study found smaller MEP sizes in medicated chronic patients;54 1 study found increased MEP sizes in medicated patients with chronic schizophrenia;88 1 study found no significant differences between patients with recent-onset and multi-episode schizophrenia, people at risk and healthy controls; 1 study found smaller MEP sizes in people at risk compared to patients with first-episode schizophrenia and healthy controls45
Duration of cortical silent period	Four studies found no significant differences between medicated patients with chronic schizophrenia and healthy controls;45,86,93,95 2 studies reported significantly shorter CSP duration in medicated and unmedicated patients with chronic schizophrenia;84,96 1 study found longer CSP duration in medicated patients with chronic schizophrenia and people at risk, and no significant difference between the 2 groups;54 1 study reported longer CSP duration in patients with first-episode schizophrenia compared to people at risk and healthy controls, and no difference between the latter 2 groups;58 1 study reported longer CSP duration in patients for the 130% of the RMT but not for 90% maximum stimulator output94
Short-latency afferent inhibition	One study reported normal short-latency afferent inhibition in patients compared to healthy controls97
Transcallosal inhibition	Two studies reported increased duration of transcallosal inhibition in patients who used the single-pulse paradigm.79,80
Short-interval intracortical inhibition	Eight studies reported reduced SICI in medicated patients with chronic schizophrenia,45,54,60,81,82,89,93 patients with recent-onset schizophrenia60 and medicated patients with first-episode schizophrenia;58 1 study reported unchanged SICI in patients with chronic schizophrenia and medication resistance;95 1 study reported unchanged SICI in medicated patients with chronic schizophrenia at interstimulus intervals of 1, 2, 3 and 4 ms but when data for the 4 interstimulus intervals were pooled, patients showed reduced SICI;84 1 study reported reduced SICI in people at risk;56 1 study found unchanged SICI in people at risk.54
Intracortical facilitation	Seven studies reported no significant differences between medicated patients with chronic schizophrenia and healthy controls;45,54,60,82,84,93,95 1 study found no significant difference between people at risk, medicated patients with chronic schizophrenia and healthy controls;54 1 study reported mixed results: reduced intracortical facilitation in medicated patients with chronic schizophrenia compared to healthy controls in 1 experimental session, but no difference between the groups in another session that was 4~8 days apart89
Long-interval intracortical inhibition	One study found no differences between medicated patients and healthy controls93

CSP = cortical silent period; EMG = electromyography; GABA = γ-aminobutyric acid; LICI = long-interval intracortical inhibition; MEP = motor evoked potential; RMT = resting motor threshold; SICI = short=interval intracortical inhibition; TMS = transcranial magnetic stimulation.

^*Unless otherwise specified, comparisons were made between patient groups or people at risk of psychosis and healthy controls.