A NEW ANGLE ON TRANSCRANIAL MAGNETIC STIMULATION COIL ORIENTATION: A TARGETED NARRATIVE REVIEW

activity), and 4) GABAA agonist, lorazepam (2.5mg).Corticomotor excitability was measured with motor-evoked potentials (MEPs) before and after rTMS.TMS was delivered to the left motor cortex at 80% of resting motor threshold.Both 10-Hz and iTBS otherwise aligned with FDA-cleared protocols.Statistical comparisons were conducted with repeated measures ANOVA.Results: For 10-Hz, d-cycloserine enhanced MEPs relative to placebo (Z=-3.74,p=.001) which was abolished when dextromethorphan was added (Z=-.391, p=.695), while Lorazepam decreased MEPs [Z=-6.06,p<.001].iTBS was also enhanced by dcycloserine (Z=-5.13,p<.001), but unlike 10-Hz, this effect persisted with dextromethorphan (Z=-5.30,p<.001) and there was no reduction by lorazepam (Z=-.447,p=.654).Conclusions: Our preliminary results suggest that 10-Hz rTMS works through LTP alone, while iTBS appears to reduce GABA receptor expression as well.This study is the first to investigate the synaptic-level mechanisms of 1) the 3000 pulse 10-Hz protocol, 2) the effects of NMDA and GABA receptor modulation, 3) iTBS and 10-Hz protocols.