It is also believed that GAD67 is present at higher amounts in tonically active neurons. These are said to be tonically active. This phenomenon is of great value especially for tonically active smooth muscle. Like the GPi, the GPe is a tonically active inhibitory nucleus. In lexical words, one syllable will be tonically prominent. It is thought that hypothalamic neurons tonically produce endocannabinoids that work to tightly regulate hunger. Purkinje cells of the cerebellar cortex tonically inhibit deep nuclear cells. Calponin tonically inhibits the ATPase activity of myosin in smooth muscle. The thalamus, however, is tonically inhibited by the basal ganglia. Like calponin, caldesmon tonically inhibits the ATPase activity of myosin in smooth muscle.