OP 2. Transfer of cognitive training across magnitude dimensions achieved with concurrent brain stimulation of the parietal lobe

(so-tDCS) was applied over the frontal cortex of rats during slowwave sleep (SWS) and its effects on memory consolidation in the one-trial object-place recognition task (OPR) were examined. The OPR is a spatial memory task, and has been shown to depend critically on intact hippocampal function (Bussey et al., 2000; Mumby et al., 2002). It does not involve stressful procedures or food deprivation; it is based on the rodents’ natural behavior, i.e., novelty preference (Ennaceur et al., 1997) and allows for intra-subject testing for stimulation and sham conditions. Previous findings showed the dependency of this task on sleep containing a large amount of slow wave activity within the retention interval (Binder et al., 2012; Inostroza et al., 2012). In a within subject design, 12 rats received one so-tDCS over the frontal cortex and one sham-tDCS session immediately after learning during early SWS. 24 h after learning, the test session in the OPR task took place to investigate the effects of so-tDCS on long-term memory. Results: As depicted in Fig. 1, animals were only able to solve the task following so-tDCS, but failed to do so in the sham condition lacking so-tDCS. EEG spectral power indicated a transitory enhancement of endogenous SO activity after cessation of so-tDCS. Conclusion: We conclude that SO play a causal role for sleep dependent memory consolidation, and state that oscillatory tDCS is a highly valuable tool to further investigate the function of endogenous cortical network activity.