Directional Couplings Between Electroencephalogram and Interbeat Intervals Signals in Awake State and Different Stages of Sleep. - Ekaterina I. Borovkova; Alexey N. Hramkov; Anatoly S. Karavaev; Vladimir I. Ponomarenko; Mikhail D. Prokhorov; Yurii M. Ishbulatov; Thomas Penzel (EMBC, 2021)