Nigrostriatal dopaminergic neurons exhibit tonic and phasic patterns of neuronal firing activity. Rapid eye movement sleep can be subclassified into tonic and phasic modes. Local anesthetics work by inducing a phasic block state in the targeted neurons. These subunits fire spontaneously in either a tonic or a phasic fashion. Phasic neurons are the opposite and only fire an action potential when movement occurs. In contrast, phasic receptors adapt rapidly to a stimulus. There are two general modes of entrainment&colon; phasic and continuous. B. Phase A involves phasic events, in other words, not continuous. They have been phasic, with recovery and relapse.