  We analyze partial synchronization patterns in a network of FitzHugh-Nagumo
oscillators with empirical structural connectivity measured in healthy human
subjects. We report a dynamical asymmetry between the hemispheres, induced by
the natural structural asymmetry. We show that the dynamical asymmetry can be
enhanced by introducing the inter-hemispheric coupling strength as a control
parameter for partial synchronization patterns. We specify the possible
modalities for existence of unihemispheric sleep in human brain, where one
hemisphere sleeps while the other remains awake. In fact, this state is common
among migratory birds and mammals like aquatic species.
