Table 3.

A summary of the main findings of the studies investigating the effects of TMS on the glutamatergic system.

Glutamatergic system
Study	Design	Population (n)	Intervention	Result
Fregni et al., 2011	Crossover randomized double-blind placebo-controlled study	Chronic pancreatitis/visceral pain N=17 Sham group: 8 Real group: 9	Ten sessions of real or sham rTMS of SII spectroscopy evaluation.	No significant changes in glutamate and N-acetyl aspartate (NAA) levels for either left or right SII-rTMS in the sham group Significant increases in glutamate and NAA levels in the active group
De Andrade et al., 2013	Crossover randomized double-blind placebo-controlled study	Healthy volunteers. N=36	Active rTMS of the right M1; active rTMS of the right DLPFC/PMC; or sham, after either intravenous saline or ketamine pretreatment	Ketamine significantly decreased the analgesic effects of both M1- and DLPFC/PMC-TMS
Wischnewski et al., 2018	Clinical study	Healthy volunteers. N=11	20 Hz beta tACS to M1, after intake of dextromethorphan (DMO) or placebo.	Motor evoked potential significantly increased after tACS in placebo group compared with baseline. However, this effect was not found in the DMO group. Resting-state beta oscillatory activity increases when compared to baseline in the placebo group, but not in the DMO group