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Does tDCS over the primary motor cortex have an effect on the consolidation of motor memories? O. Rroji, L. Pauwels, E. Bekkers, N. Wenderoth Centre forMovement Control and Neuroplasticity, Dept. Biomedical Kinesiology, KU Leuven, Belgium Introduction: Transcranial direct current stimulation (tDCS)(1) is a non-invasive, painless cortical stimulation technique(2) that is well tolerated by healthy subjects and patients. Recent studies have demonstrated that non-invasive brain stimulation enhances memory formation and cortical plasticity for a variety of tasks including visuo-motor coordination(3), implicit motor learning and probabilistic classification learning in healthy volunteers. Here we tested whether tDCS affects also use-dependent plasticity, i.e. increase in neural and behavioral efficiency as a consequence of repeated practice. Methods: 14 healthy young volunteers (age 18 to 30, 6 females, 4 left handed) were involved. The subjects had to practice to flex their non-dominant thumb as fast as possible for 10 blocks, consisting of 20 movements each (1 mov every 3s). Between blocks there were 1min break to prevent fatigue, in total 20min. In half of the subjects, real tDCS was applied during the first training session with the anode mounted over the contralateral primary motor cortex(M1) and the cathode placed on the contralateral shoulder. Results: First analyses indicate that real tDCS enhanced retention performance 1 day and particularly 1 week after training, as indicated by a significant training x stimulation interaction (F(16,160)=4.09, p<0.0001) which was revealed by an analysis of variance for repeated measurements. In an ongoing experiment we are testing whether placement of tDCS electrodes and the amount of training will show a different result compared to the previous experiment. Discussion: Our data show for the first time that tDCS has a positive effect on use-dependent plasticity. Importantly, tDCS did not affect training performance per se but rather memory consolidation. Its beneficial effect seems to be enhanced when the motor memory is repeatedly reactivated even if reactivation occurs one day after the tDCS intervention. Our results might have important implications for increasing the efficiency of motor practice in healthy subjects and rehabilitation settings. References: 1.Paulus W. Transcranial direct current stimulation (tDCS). Suppl Clin Neurophysiol 56:249–54., 2003. 2.Nitsche M. A., Paulus W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J Physiol 27:633–9.2000. 3.Reis J. et al. Noninvasive cortical stimulation enhances motor skill acquisition over multiple days through an effect on consolidation. PNAS 106:1590-1595.2009.