inhibition. The ventral area of the zona incerta has been described as having "a network of GABAergic cells with widespread interconnections, so that cells in one subsector may influence the activity of cells in a different subsector". The zona incerta together with the hypothalamus is one of the two areas of the brain that produces the neuropeptide melanin concentrating hormone. Dopaminergic ones are also more prevalent. There are in addition populations of cells producing somatostatin, angiotensin II and melanocyte stimulating hormone. Connections The zona incerta has connections to the cerebral cortex, diencephalon, basal ganglia, brainstem and spinal cord. Cerebral cortex Projections to the zona incerta arise across the cortical mantel from the frontal to the occipital lobes. The heaviest projections are from cingulate cortex, frontal and parietal areas, but also projections from the medial prefrontal cortex have been reported. The head area of the body seems from these areas to have the largest representation in the zona incerta. These projections preferentially go to cortical layer I neurons. There are projections from the zona incerta back to the cerebral cortex. Diencephalon Projections with the diencephalon are reciprocal and mainly to the thalamus such as the intralaminar nucleus (parafascicular nucleus and central lateral nucleus) and higher-order nuclei such as the lateral posterior nucleus. The zona incerta avoids the thalamus nuclei of the primary sensory areas such as the ventral posterior nucleus of the somatosensory system and the lateral geniculate of the visual system. Rostral zona incerta also sends inhibitory projections to paraventricular thalamus with GABAergic neurotransmission. Hypothalamus Projections to the hypothalamus through incertohypothalamic pathway go mainly to the paraventricular nucleus areas in the anterior hypothalamus, lateral hypothalamus, lateral preoptic area, horizontal diagonal band of Broca, and the parvocellular region of the paraventricular nucleus. Basal ganglia Zona incerta is connected in the basal ganglia to the substantia nigra (both pars compacta and pars reticulata) and pedunculopontine tegmental nucleus (but only its pars dissipata area). It also has less important connections to the entopeduncular nucleus and globus pallidus. These projections are glutamatergic and excitatory rather than GABAergic and inhibitory. The zona incerta also receives input from these areas. Cerebellum The cerebellum sends a significant number of fibers to the zona incerta. These projections originate from various cerebellar nuclei and are glutamatergic. Given the cerebellar contributions to motor learning, timing and coordination, the interactions between the cerebellum with the zona incerta are likely to have