Article The Effect of Parietal and Cerebellar Transcranial Direct Current Stimulation on Bimanual Coordinated Adaptive Motor Learning Atefeh Azarpaikan 1 , Hamid Reza Taherii Torbati 1 , Mehdi Sohrabi 1 , Reza Boostani 2 , and Majid Ghoshuni 3 1 Department of Motor Behavior, Faculty of Physical Education and Sport Science, Ferdowsi University of Mashhad, Iran 2 Department of Neurology, Mashhad University of Medical sciences, Mashhad, Iran 3 Department of Biomedical Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran Abstract: Many daily activities, such as typing, eating, playing the piano, and passing the ball in volleyball, require the proficient coordination of both hands. In this study, the effects of anodal transcranial direct current stimulation (atDCS) on the acquisition, retention, and transfer of bimanual adaptive motor tasks were investigated. To this end, 64 volunteers (M age = 24.36 years; SD = 2.51; 16 females) participated in this double-blind study and were categorized randomly into 4 groups. During the pretest, posttest, 24-h and 48-h retention, and transfer tests, two forms of bimanual coordination (BC) of the Vienna test system were performed. Between the pretest and posttest, all participants were trained in a bimanual coordination adaptive task with concurrent brain stimulation (1.5 mA for 15 min) for two consecutive days. The first experimental group (parietal-stim) received atDCS over the right parietal cortex (P4), while the second experimental group (cerebellar-stim) received atDCS over the bilateral cerebellum (2.5 cm bilateral to the inion). The third group (sham) received a sham stimulation. Finally, the control group did not receive any stimulation at all (control). Repeated-measure analysis of variance (ANOVA RM ) results indicated that parietal tDCS affected motor performance in the posttest, while overall mean duration and overall error mean duration of movement decreased. The results also revealed a significant impact of cerebellar tDCS on the posttest, 24-h and 48-h retention, and transfer tests. The overall mean duration and overall error mean durations of movement in this group were significantly lower than those in the other groups. Accordingly, we found evidence that atDCS over the cerebellum leads to more improvement in motor performance and transfer in a bimanual coordination task than atDCS over the right parietal. Finally, these results point to the possibly beneficial application of atDCS for learning and recovery of bimanual motor skills, especially when subjects are faced with a new challenging situation. Keywords: parietal cortex, cerebellum, transcranial direct current stimulation, bimanual coordination Adaptive learning is the ability to learn new motor patterns when the level of performance is improved by decreasing errors in a dynamic environment. It depends on certain neural and behavioral mechanisms (Krakauer, 2009). The phenomenon known as neuroplasticity can be one of the main triggers of adaptive motor learning at different levels of central neural networks (Galea, Vazquaz, Pasricha Orban de Xivry, & Celnik, 2011). Two of the most important aspects of adaptive learning in daily life are performance and learning of bimanual tasks. Over half of every given day for the average individual is spent taking and manipu- lating objects and working with both hands (Kilbreath & Heard, 2005). Skilled and accurate bimanual movements are involved in everyday life including sport, work, or other activities. Studies on brain functions have shown that different regions of the brain are active during motor adaptive learn- ing, such as primary motor cortex (M1), visual and parietal cortex, pre-frontal cortex, and the cerebellum (Anderson, Alcantara, & Greenough, 1996; Kleim et al., 2002; Kwon, Nam, & Park, 2012). The cerebellum and parietal cortex are two of the key target structures for the procedures of motor adaptive learning, especially when it comes to multi-limb movements (Grimaldi et al., 2016; Pergolizzi, Ó 2019 Hogrefe Publishing Journal of Psychophysiology (2021), 35(1), 1–14 https://doi.org/10.1027/0269-8803/a000254 https://econtent.hogrefe.com/doi/pdf/10.1027/0269-8803/a000254 - Saturday, September 17, 2022 9:51:02 AM - IP Address:3.226.244.221