@article{NguemeniStiehlHiewetal.2021,
  author    = {Nguemeni, Carine and Stiehl, Annika and Hiew, Shawn and Zeller, Daniel},
  title     = {No Impact of Cerebellar Anodal Transcranial Direct Current Stimulation at Three Different Timings on Motor Learning in a Sequential Finger-Tapping Task},
  series = {Frontiers in Human Neuroscience},
  volume    = {15},
  journal   = {Frontiers in Human Neuroscience},
  issn      = {1662-5161},
  doi       = {10.3389/fnhum.2021.631517},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225477},
  year      = {2021},
  abstract  = {Background: Recently, attention has grown toward cerebellar neuromodulation in motor learning using transcranial direct current stimulation (tDCS). An important point of discussion regarding this modulation is the optimal timing of tDCS, as this parameter could significantly influence the outcome. Hence, this study aimed to investigate the effects of the timing of cerebellar anodal tDCS (ca-tDCS) on motor learning using a sequential finger-tapping task (FTT). Methods: One hundred and twenty two healthy young, right-handed subjects (96 females) were randomized into four groups (During\(_{sham}\), Before, During\(_{real}\), After). They performed 2 days of FTT with their non-dominant hand on a custom keyboard. The task consisted of 40 s of typing followed by 20 s rest. Each participant received ca-tDCS (2 mA, sponge electrodes of 25 cm\(^{2}\), 20 min) at the appropriate timing and performed 20 trials on the first day (T1, 20 min). On the following day, only 10 trials of FTT were performed without tDCS (T2, 10 min). Motor skill performance and retention were assessed. Results: All participants showed a time-dependent increase in learning. Motor performance was not different between groups at the end of T1 (p = 0.59). ca-tDCS did not facilitate the retention of the motor skill in the FTT at T2 (p = 0.27). Thus, our findings indicate an absence of the effect of ca-tDCS on motor performance or retention of the FTT independently from the timing of stimulation. Conclusion: The present results suggest that the outcome of ca-tDCS is highly dependent on the task and stimulation parameters. Future studies need to establish a clear basis for the successful and reproducible clinical application of ca-tDCS.},
  language  = {en}
}
@article{NguemeniHiewKoegleretal.2021,
  author    = {Nguemeni, Carine and Hiew, Shawn and K{\"o}gler, Stefanie and Homola, Gy{\"o}rgy A. and Volkmann, Jens and Zeller, Daniel},
  title     = {Split-belt training but not cerebellar anodal tDCS improves stability control and reduces risk of fall in patients with multiple sclerosis},
  series = {Brain Sciences},
  volume    = {12},
  journal   = {Brain Sciences},
  number    = {1},
  issn      = {2076-3425},
  doi       = {10.3390/brainsci12010063},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252179},
  year      = {2021},
  abstract  = {The objective of this study was to examine the therapeutic potential of multiple sessions of training on a split-belt treadmill (SBT) combined with cerebellar anodal transcranial direct current stimulation (tDCS) on gait and balance in People with Multiple Sclerosis (PwMS). Twenty-two PwMS received six sessions of anodal (PwMS\(_{real}\), n = 12) or sham (PwMS\(_{sham}\), n = 10) tDCS to the cerebellum prior to performing the locomotor adaptation task on the SBT. To evaluate the effect of the intervention, functional gait assessment (FGA) scores and distance walked in 2 min (2MWT) were measured at the baseline (T0), day 6 (T5), and at the 4-week follow up (T6). Locomotor performance and changes of motor outcomes were similar in PwMS\(_{real}\) and PwMS\(_{sham}\) independently from tDCS mode applied to the cerebellum (anodal vs. sham, on FGA, p = 0.23; and 2MWT, p = 0.49). When the data were pooled across the groups to investigate the effects of multiple sessions of SBT training alone, significant improvement of gait and balance was found on T5 and T6, respectively, relative to baseline (FGA, p < 0.001 for both time points). The FGA change at T6 was significantly higher than at T5 (p = 0.01) underlining a long-lasting improvement. An improvement of the distance walked during the 2MWT was also observed on T5 and T6 relative to T0 (p = 0.002). Multiple sessions of SBT training resulted in a lasting improvement of gait stability and endurance, thus potentially reducing the risk of fall as measured by FGA and 2MWT. Application of cerebellar tDCS during SBT walking had no additional effect on locomotor outcomes.},
  language  = {en}
}