[2][3] A hundred and thirty years later in 2007, Nadia Urbain and Martin Deschênes of Université Laval noted that the "zona incerta is among the least studied regions of the brain; its name does not even appear in the index of many textbooks.
Zona incerta also has connections to the amygdala, basal forebrain, the osmoreceptors in the subfornical organ, olfactory bulb, posterior pituitary and habenula.
Some of these projections appear in register; the representation of the same body part in cortex and spinal cord connect to the same areas in the zona incerta.
This control is related to its effects upon the nearby posterior hypothalamus with which it shares similar connections and neurochemically defined cell types.
[3] Activation of GABA neurons in rostral zona incerta evokes binge eating behavior with a preference to sweet and high-fat food.
[16] Zona incerta has also been found to modulate both innate and learned defensive behaviors through its projections to the excitatory neurons of the dorsolateral and ventrolateral compartments of the periaqueductal gray.
[26] Somatostatin-expressing neurons coordinate the positive effects of a preweening infant's relationship with its mother damping its behavioral distress (crying) after separation upon reunion, a phenomenon contrary to their role in increasing anxiety in adults.
[15] Electrical or chemical stimulation of the zona incerta creates limbic-related movements, such as those associated with defense orientation and copulation.
It has moreover been proposed that the zona incerta provides a top-down disinhibitory mechanism of this gating when there is sensory-motor activity such as the tactile use of whiskers.
By contrast, increased cholinergic activity during wakefulness and enhanced vigilance suppresses zona incerta -mediated inhibition, thereby ungating posterior thalamus responses to ascending inputs.
[30] The GABAergic input received from the cerebral cortex has been suggested to synchronize thalamocortical and brainstem rhythms by providing a link between basal ganglia output and the cerebello-thalamo cortical loop.
The zona incerta is in a position to form a primal synaptic interface of the diencephalon, linking diverse sensory channels to appropriate visceral, arousal, attention and posture-locomotion responses.
Deep brain stimulation of the subthalamic nucleus in those with Parkinson's disease has identified the zona incerta as a promising target area for effective therapy.
[10] This also occurs without dysarthria and disequilibrium as this stimulation does not interrupt proprioceptive sensation and the processing of the fine motor skill movements of vocal cords.
The conduction of abnormal oscillations generated in the basal ganglia in Parkinson Disease to the ventral lateral nucleus via zona incerta would therefore explain this paradox and also explain why we observed such a potent anti-tremor effect from stimulating zona incerta in our patients with Parkinson Disease"[10] The study further noted that deep brain stimulation upon the zona incerta "is effective in suppressing all components of tremor affecting both the distal and proximal part of the body.
These results, if replicated in larger randomised controlled studies, have important implications for our current surgical management of patients with tremor and point to a more promising target area than the ventral lateral nucleus of the thalamus.
Recent research suggests that the development and maintenance of such pain could link to abnormal inhibitory regulation by the zona incerta of the posterior thalamus.