ABSTRACT
Theta-burst stimulation (TBS) is a patterned form of repetitive transcranial magnetic stimulation (rTMS) that has been used to induce long-term modulation (plasticity) of corticospinal excitability in a drastically shorter duration protocol than conventional rTMS protocols. In this study we tested the reliability of the effects of two well defined TBS protocols, continuous TBS (cTBS) and intermittent TBS (iTBS), especially in relation to sham TBS, within and across the same 24 participants. All TBS protocols were repeated after approximately 1 month to assess the magnitude and reliability of the modulatory effects of each TBS protocol. Baseline and post-TBS changes in motor evoked potentials (MEP-measure of corticospinal excitability) amplitudes were compared across the cTBS, iTBS and sham TBS protocols and between the initial and retest visits. Overall, across participants, at the initial visit, iTBS facilitated MEPs as compared to baseline excitability, with sham eliciting the same effect. cTBS did not show a significant suppression of excitability compared to baseline MEPs at either visit, and even facilitated MEPs above baseline excitability at a single time point during the repeat visit. Otherwise, effects of TBS were generally diminished in the repeat visit, with iTBS and sham TBS replicating facilitation of MEPs above baseline excitability at similar time points. However, no protocol demonstrated consistent intra-individual modulation of corticospinal excitability upon retest. As the first study to test both iTBS and cTBS against sham TBS across repeat visits, our findings challenge the efficacy and reliability of TBS protocols and emphasize the importance of accounting for sham effects of TBS. Furthermore, given that therapeutic effects of TBS are hypothetically derived from consistent and repeated modulation of brain activity, the non-replicability of plasticity and sham effects call into question these basic mechanisms.
Subject(s)
Evoked Potentials, Motor , Theta Rhythm , Transcranial Magnetic Stimulation/methods , Adolescent , Adult , Brain/physiology , Female , Humans , Long-Term Potentiation , Male , Middle Aged , Neuromuscular Junction/physiology , Reproducibility of Results , Transcranial Magnetic Stimulation/standardsABSTRACT
BACKGROUND: With regard to the willing and starting tobacco smoking among young people in Iran. The aim of the study was to model the underlying factors in predicting the behavior of tobacco smoking among employed youth and students in Iran. METHODS: In this analytical cross-sectional study, based on a random cluster sampling were recruited 850 high school students, employed and unemployed youth age ranged between 14 and 19 yr from Iran. The data of demographic and tobacco smoking related variables were acquired via a self-administered questionnaire. A series of univariate and multivariate logistic regressions were performed respectively for computing un-adjusted and adjusted Odds Ratios utilizing SPSS 17 software. RESULTS: A number of 189 persons (25.6%) were smoker in the study and the mean smoking initiation age was 13.93 (SD= 2.21). In addition, smoker friend, peer persistence, leaving home, and smoking in one and six month ago were obtained as independent predictors of tobacco smoking. CONCLUSIONS: The education programs on resistance skills against the persistence of the peers, improvement in health programs by governmental interference and policy should be implemented.
