Force and complexity of tongue task training influences behavioral measures of motor learning

Relearning of motor skills is important in neurorehabilitation. We investigated the improvement of training success during simple tongue protrusion (two force levels) and a more complex tongue-training paradigm using the Tongue Drive System (TDS). We also compared subject-based reports of fun, pain, fatigue, and motivation between paradigms. Three randomized sessions and one control experiment were performed. Sixteen healthy subjects completed two different 1-h sessions of simple tongue training with 1 N and 3 N, respectively, and one TDS session. After 1 wk, six out of 16 subjects participated as experienced subjects with six naive subjects in a control experiment with 2 × 5-min TDS training separated by a 30-min rest. Performance improved during training in all sessions. The mean ± SEM relative increase in success was 80 ± 12% (1 N), 52 ± 11% (3 N), and 285 ± 45% (TDS). In the control experiment the experienced group performed equal to the last 5 min of their first TDS session and neither group improved during rest. Training with the TDS was rated as more fun, less painful, less fatiguing, and more motivating compared with simple tongue training. In conclusion, force level and complexity of tongue training influences behavioral aspects of tongue motor learning.