There are two types of neurons in the pre-BötC: nonpacemaker and pacemaker neurons. Nonpacemaker neurons enter either a tonic or a quiescent firing state, whereas the pacemaker neurons have spontaneous bursting potential. Pacemaker neurons can further be subdivided into cadmium sensitive (CS) and cadmium insensitive (CI) pacemaker neurons. Bursting in CS neurons are mediated by ICAN, a nonspecific cation current, whereas CI is dependent upon the persistent sodium current, (INAP). Inhibiting these currents in the pacemaker subtypes cease their ability to spontaneously burst in synaptic isolation. Although they are a major contributor of inward current, these two currents are not the only ones mediating pacemakers. They also contribute to nonpacemaker neuronal properties.