Theta-burst pulse number and cortical excitability

IHere we present the first parametric sham-controlled study to explore the relationship between TBS pulse number (both cTBS and iTBS) and motor cortex excitability. The goal of these experiments was to systematically evaluate the effect of TBS dose on the change in motor cortex excitability. As a refinement of previous studies, we also included an active sham condition. The primary conclusions are that (1) within iTBS protocols, 1200 pulses is significantly different from sham, resulting in a net inhibition of cortical excitability, and (2) within cTBS protocols, 3600 pulses is different than sham, resulting in a net increase in excitability. We did not, how-ever, find significant effects of the other doses relative to sham. This may be due to a high degree of intra- and interindividual variability—a finding which has been reported by many other studies in the TBS field