The phase transition with respect to the intensity of a -correlated noise source has been studied in a coupled map lattice that simulates the excitability of field-type neural tissues [7]. The entropy of lattice states versus this control parameter undergoes a qualitative change at the phase transition point. Its behavior is linear on one side of this point and it transforms to a cubic-root form on the other side. An enormously increasing susceptibility to external perturbation in the vicinity of the phase transition point leads to an observed existence of stochastic resonance in this region. Complexity induced by the external subthreshold periodic signal reaches a maximum at the phase transition point.