Variety of spatio-temporal regimes in a 2D lattice of coupled bistable FitzHugh-Nagumo oscillators. Formation mechanisms of spiral and double-well chimeras

•Variety of the dynamical regimes is studied in the 2D lattice of bistable coupled FHN oscillators.•Two types of boundary conditions are considered.•Formation mechanisms both of double-well and spiral chimeras have been revealed. We consider the dynamics of a 2D lattice of nonlocally coupled FitzHugh-Nagumo oscillators in the regime of bistability. Special attention is paid to the study of influence both of the type of boundary conditions and of the features of the oscillator interaction on the formation of wave regimes and spatiotemporal structures. It is shown that shifting the effective values of the control parameters of partial oscillators under the influence of coupling significantly changes their dynamics and can lead to switching of the dynamical regimes of the whole system. We also calculate the local indexes of sensitivity and the Lyapunov exponents to quantify the observed regimes. A spiral chimera regime is found in the lattice under study for the case of zero flux boundary conditions. It is revealed that the system is in the hyperchaotic regime for this chimera state. We also explain the mechanisms of emergence of the double-well and spiral chimera states which are realized in the lattice.