Here, we defined the after-effects induced by days of rTMS as long-term effect (LTE). Consistent with this variability in healthy subjects, another study observed that less than half of patients with major depression could achieve symptom remission after days of rTMS treatment ( Yesavage et al., 2018). Electroencephalography might represent a more thorough reflection of cortical excitability than motor evoked potentials (MEP) ( Rocchi et al., 2018). But notably, the variability may change with the readout measures. For instance, although continuous theta-burst stimulation (cTBS) was initially proposed as an inhibitory protocol ( Huang et al., 2005), a study with a larger sample size ( n = 52) indicated that only 42% subjects respond to the stimulation as expected ( Hamada et al., 2013). However, high variability of rTMS after-effects has also been reported in both neuroscientific and clinical studies ( Hamada et al., 2013 Yesavage et al., 2018).
It has been widely used to map brain function of healthy subjects or alleviate clinical symptoms for neuropsychological patients. Repetitive transcranial magnetic stimulation (rTMS) is a powerful technique that could non-invasively modulate neural activity in human brain ( Allen et al., 2007). These imaging evidences indicate that one-session rTMS can aid to predict the regions responsive to long-term stimulation and the individualized response degree. In an independent cohort, the after-effects of rTMS on ParaCG and short- to long-term prediction were reproduced at the region-of-interest level. Leave-one-out cross-validation indicated that the LTE in ParaCG could be predicted by the STE after real but not sham stimulations. Region-of-interest analysis indicated that the resting-state functional connectivity between SMA and ParaCG increased after real stimulation, while no significant change was found after sham stimulation. Compared to the baseline, significant STE and LTE were found in the bilateral paracentral gyrus (ParaCG) after real stimulation, suggesting shared neural correlates of short- and long-term stimulations. The SMA connectivity changes after the first cTBS and after 5 days of stimulation were defined as STE and LTE, respectively. Resting-state functional magnetic resonance imaging (fMRI) data were acquired at the first (before and after the first stimulation) and sixth experimental day. A primary cohort of 38 healthy participants underwent five daily sessions of real or sham continuous theta-burst stimulation (cTBS) on the left SMA. This study aims to explore whether the after-effects of 5-day rTMS on supplementary motor area (SMA) network could be predicted by one-session response. However, the relation between the short-term effect (STE) and long-term effect (LTE) of rTMS is largely unknown. To understand the neural mechanism of repetitive transcranial magnetic stimulation (rTMS), the after-effects following one session or multiple days of stimulation have been widely investigated.
2Department of Medical Psychology, Chaohu Clinical Medical College, Anhui Medical University, Hefei, China.
1Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China.