Zona incerta = "The area of unclear function" (Forel, 1877); a name which is still valid.

Zona incerta is a kernel on hay. and we. side in the subthalamus region. It is ventrally sandwiched between the dorsal thalamus and hypothalamus and passes laterally into the reticular thalamus nucleus. The zona incerta and the reticular thalamus nucleus are both considered to constitute diencephalic extensions of formatio reticularis.

Zona incerta consists of a highly mixed group of neurons, both cytoarchitecturally and chemoarchitecturally. Here are e.g. those who produce angiotensin II, orexin, somatostatin and here are located the dopamine-producing cell group A 13 and parts of the cell group A 11. Note the proximity and partial fusion with the hypothalamus!

Zona incerta is thought to receive signals from, and transmit signals to, virtually all regions of the central nervous system. The signal traffic is in most cases of a return nature. With respect to the spinal cord, the hind horns appear to deliver afferens via the tractus spino-thalamicus to, and the front horns to receive efferens from the zona incerta.

Attempts have been made to divide the zona incerta into different reaction-reception sectors
1/ reception of signals from the retina and various sections of the visual cortex
2/ Reception of signals from the colliculus inferior and the auditory nuclei
3/ reception of signals from the spinal cord, medulla and sensorimotor cortex
4/ Reception of signals from the limbic system
5/ Reception of signals from the cerebellum and nucleus ruber
The reception sectors appear to be part of a local coordinating network which in turn has return links with the one on the opposite side.

Zona incerta is further considered an important player in the following contexts:

Visceral activities/sensations such as thirst, appetite, control of body temperature and release of sex hormones. Note the proximity and partial fusion with the hypothalamus!

Awakening and activation of the cerebral cortex via signaling to the acetylcholine-producing nuclear groups in the mesencephalon and in the basal forebrain.

Directing attention to a specific area of the room or on/in one's own body. Here, the signal relationships with the somatosensory cortex, colliculus superior, gaze direction centers and spinal cord are of importance.

Posture and movements are affected via signaling over e.g. the cerebellum, nucleus ruber, substantia nigra, GPi. Experiments on male rats have shown that a small injury in the zona incerta makes the otherwise sexually interested animal unable to perform the copulation movements.

Zona incerta should perhaps be perceived as a kind of emergency brake with the possibility of interrupting ongoing activities and directing all attention to the sensory information that is currently collected, processed and classified as THREATENING (ref below!).

Electrical stimulation - so-called Deep Brain Stimulation; DBS - in zona incerta has been shown to attenuate the symptoms of Parkinson's disease and Chronic pain syndrome.

Mitrofanis, J. Some certainity for the "Zone of uncertainity"? Exploring the functions of the zona incerta. Neuroscience 130 (2005) 1–15.
Watson C. Lind, C. R. P. Thomas, M. G. The anatomy of the caudal zona incerta in rodents and primates. J Anat. 2014 Feb; 224(2): 95–107.

Uppslagsverket

Zona periventricularis, hypothalamus

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