PMID- 27766075 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20200930 IS - 1662-5161 (Print) IS - 1662-5161 (Electronic) IS - 1662-5161 (Linking) VI - 10 DP - 2016 TI - Measures to Predict The Individual Variability of Corticospinal Responses Following Transcranial Direct Current Stimulation. PG - 487 LID - 487 AB - Individual responses to transcranial direct current stimulation (tDCS) are varied and therefore potentially limit its application. There is evidence that this variability is related to the contributions of Indirect waves (I-waves) recruited in the cortex. The latency of motor-evoked potentials (MEPs) can be measured through transcranial magnetic stimulation (TMS), allowing an individual's responsiveness to tDCS to be determined. However, this single-pulse method requires several different orientations of the TMS coil, potentially affecting its reliability. Instead, we propose a paired-pulse TMS paradigm targeting I-waves as an alternative method. This method uses one orientation that reduces inter- and intra-trial variability. It was hypothesized that the paired-pulse method would correlate more highly to tDCS responses than the single-pulse method. In a randomized, double blinded, cross-over design, 30 healthy participants completed two sessions, receiving 20 min of either anodal (2 mA) or sham tDCS. TMS was used to quantify Short interval intracortical facilitation (SICF) at Inter stimulus intervals (ISIs) of 1.5, 3.5 and 4.5 ms. Latency was determined in the posterior-anterior (PA), anterior-posterior (AP) and latero-medial (LM) coil orientations. The relationship between latency, SICF measures and the change in suprathreshold MEP amplitude size following tDCS were determined with Pearson's correlations. TMS measures, SICI and SICF were also used to determine responses to Anodal-tDCS (a-tDCS). Neither of the latency differences nor the SICF measures correlated to the change in MEP amplitude from pre-post tDCS (all P > 0.05). Overall, there was no significant response to tDCS in this cohort. This study highlights the need for testing the effects of various tDCS protocols on the different I-waves. Further research into SICF and whether it is a viable measure of I-wave facilitation is warranted. FAU - Nuzum, Nathan D AU - Nuzum ND AD - School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia. FAU - Hendy, Ashlee M AU - Hendy AM AD - School of Exercise and Nutrition Sciences, Deakin University Geelong, VIC, Australia. FAU - Russell, Aaron P AU - Russell AP AD - Institute for Physical Activity and Nutrition (IPAN), Deakin University Geelong, VIC, Australia. FAU - Teo, Wei-Peng AU - Teo WP AD - Institute for Physical Activity and Nutrition (IPAN), Deakin University Geelong, VIC, Australia. LA - eng PT - Journal Article DEP - 20161006 PL - Switzerland TA - Front Hum Neurosci JT - Frontiers in human neuroscience JID - 101477954 PMC - PMC5052268 OTO - NOTNLM OT - I-waves OT - anodal tDCS OT - latency OT - short intracortical facilitation OT - transcranial magnetic stimulation EDAT- 2016/10/22 06:00 MHDA- 2016/10/22 06:01 PMCR- 2016/01/01 CRDT- 2016/10/22 06:00 PHST- 2016/03/22 00:00 [received] PHST- 2016/09/14 00:00 [accepted] PHST- 2016/10/22 06:00 [pubmed] PHST- 2016/10/22 06:01 [medline] PHST- 2016/10/22 06:00 [entrez] PHST- 2016/01/01 00:00 [pmc-release] AID - 10.3389/fnhum.2016.00487 [doi] PST - epublish SO - Front Hum Neurosci. 2016 Oct 6;10:487. doi: 10.3389/fnhum.2016.00487. eCollection 2016.