P094 Method for EEG guided transcranial Electrical Stimulation without models

effects not achievable neither with rTMS alone nor with operant learning alone. Methods: Experimental approach: Forty-six subjects were randomly assigned to three experimental groups. Experimental groups 1 & 2 received a psychophysical pretest of tactile discrimination abilities with the left ring finger, a training procedure to improve performance with this finger, and a posttest. In experimental group 1 the training procedure was combined with 15 Hz rTMS over the primary sensory cortex (SI) while in experimental group 2 the training was combined with sham rTMS. In the third experimental group, psychophysical preand posttests of tactile discrimination abilities were assessed. However, they received 15 Hz rTMS over SI without training. Computational approach: As a preliminary simulation trial we developed a neural model, which enabled us to discriminate between the encoding and decoding of particular input frequency represented in several scenarios. Results: Combining rTMS with operant learning induced longlasting after-effects not achievable neither with rTMS alone nor with operant learning alone. A conceptual framework for the efficiency of combining cortical stimulation with operant learning can be derived from the Bienens tock–Cooper–Munro theory of bidirectional synaptic plasticity. According to this theory the change of synaptic efficiency during learning processes is dependent on the preactivation level of the involved neural network, suggesting that high-frequency rTMS can transiently decrease the threshold for the induction of LTP-like effects and thereby gate practice-dependent plasticity. Conclusions: Our findings provide important implications for the use of rTMS in combination with operant learning as a therapeutic tool for neurorehabilitation.