Electric Stimulation to Improve Memory Consolidation During Sleep

During the last decade the interest in the manipulation of learning and memory by non-invasive techniques in humans has increased dramatically. Many studies focus on sleep as a beneficial or even necessary state for the consolidation of many types of memories. For manipulation methods of transcranial electric stimulation, TMS, deep brain stimulation, cued reactivation, sensory stimulation, especially auditory stimulation have been employed. Techniques closely comparable to the non-invasive human methods have also been developed in rodents. In addition optogenetic tools have enabled the functional causality of very specific pathways to be investigated in a complimentary way. This chapter focuses on effects induced by weak electric stimulation on consolidation during sleep but includes also manipulations aside from weak electric stimulation in a complimentary fashion. As of recent the variability in the efficiency of weak electric stimulation has come into the spotlight. Specifically, the relevance not only of the technical parameters of stimulation, but also of the electrophysiologically defined `brain state' at the time of stimulation, as well as cognitive features of the individual per se have been addressed.