  Target waves and spiral waves were discovered in the Belousov-Zhabotinsky
(BZ) reaction around 50 years ago. Inwardly rotating spiral waves, also called
the anti-spirals, were found in a BZ-AOT system about two decades ago. Many
biological systems demonstrate both spiral and anti-spirals. In the glycolytic
activity of yeast, anti-spirals are observed, whereas spiral waves are widely
studied in the context of broken cardiac waves. In the cardiac system, only
outwardly rotating normal spirals are reported. In the context of the cardiac
waves, the spirals and scrolls are widely studied in BZ reactions for
experimental study. On the other hand, the Oregonator model is considered for
the numerical simulation in correlation to the BZ reaction system. In this
study, we modified the Oregonator model a little using the same FKN mechanism,
and we present a four-variable model that can be called a modified Oregonator
system in which we observe the presence of the spiral, spiral defect, and
spiral breakup by tuning the parameters.
