Dentate nucleus

The dentate nucleus is a cluster of neurons, or nerve cells, in the central nervous system that has a dentate – tooth-like or serrated – edge. It is located within the deep white matter of each cerebellar hemisphere, and it is the largest single structure linking the cerebellum to the rest of the brain. It is the largest and most lateral, or farthest from the midline, of the four pairs of deep cerebellar nuclei, the others being the fastigial nucleus and the globose and emboliform nuclei which together are referred to as the interposed nucleus. The dentate nucleus is responsible for the planning, initiation and control of voluntary movements. The dorsal (towards the back of the body) region of the dentate nucleus contains output channels involved in motor function, which is the movement of skeletal muscle, while the ventral (towards the belly or front of the body) region contains output channels involved in nonmotor function, such as conscious thought and visuospatial function.Dissection of brain-stem. Lateral view.Deep dissection of brain-stem. Lateral view.Deep dissection of brain-stem. Lateral view.Rhomboid fossa.2° (Spinomesencephalic tract → Superior colliculus of Midbrain tectum) The dentate nucleus is a cluster of neurons, or nerve cells, in the central nervous system that has a dentate – tooth-like or serrated – edge. It is located within the deep white matter of each cerebellar hemisphere, and it is the largest single structure linking the cerebellum to the rest of the brain. It is the largest and most lateral, or farthest from the midline, of the four pairs of deep cerebellar nuclei, the others being the fastigial nucleus and the globose and emboliform nuclei which together are referred to as the interposed nucleus. The dentate nucleus is responsible for the planning, initiation and control of voluntary movements. The dorsal (towards the back of the body) region of the dentate nucleus contains output channels involved in motor function, which is the movement of skeletal muscle, while the ventral (towards the belly or front of the body) region contains output channels involved in nonmotor function, such as conscious thought and visuospatial function. The dentate nucleus is highly convoluted, with gyri (ridges on the cerebral cortex) and sulci (furrows or grooves on the cerebral cortex). Its formation is coincident with a critical period of extensive growth in the fetal dentate. The dentate nucleus becomes visible in the cerebellar white matter as early as 11–12 weeks of gestation, containing only smooth lateral (towards the side(s) or away from the midline) and medial (towards the midline) surfaces. During this time, the neurons of the dentate nucleus are similar in shape and form, being mainly bipolar cells. During 22–28 weeks of gestation, which is the critical period in fetal development of the dentate nucleus, gyral formation occurs extensively over the entire surface. Here, neurons mature into various forms of multipolar cells, and the most frequent neuronal types are medium sized to large neurons. The architecture of cerebellum has a form that resembles the structure of a crystal, so a slice anywhere in the cerebellum gives repeated architecture. The eight cerebellar nuclei, located within the deep white matter of each cerebellar hemisphere, are grouped into pairs, with one of each pair in each of the two hemispheres. As a chunk of tissue, the dentate nucleus with overlying cerebellar cortex makes up a functional unit called the cerebrocerebellum. Thus, there is a part of cerebellum that communicates exclusively with the dentate nucleus. The deep cerebellar nuclei receive the final output from the cerebellar cortex via Purkinje cells in the form of inhibition. Neurons in the cerebellar nuclei generate spontaneous action potentials despite ongoing inhibition from Purkinje cells. The cerebellar nuclei receive afferent projections from the inferior olive, lateral reticular nucleus, upper cervical and lumbar spinal segments, and the Pontine nuclei. Together, the deep cerebellar nuclei form a functional unit that provides feedback control of the cerebellar cortex by cerebellar output. The dentate nucleus is highly convoluted and can be divided into dorsal (motor) and ventral (nonmotor) domains. The ventral half is much more developed in humans than in great apes, and it appears to play an important role in fiber connection. Further, the ventral domain mediates higher cerebellar functions, such as language and cognition, as well as versatile and coordinated finger movement. While it is generally accepted that the ventral region is more recent on an evolutionary timescale, current 3-Dimensional imaging raises questions regarding this assumption, as a third axis, the rostrocaudal axis, can now be analyzed. In addition, current images show that the ventral region is not physically larger than the dorsal region in humans, as would be predicted if size increases with cognitive function. The neurons of the adult dentate are divided based on size, morphology, and function into large principal and small local circuit neurons. The large principal neurons have been classified into four primary types according to position within the dentate, shape of soma (cell body), and dendritic branching. These neurons are responsible for communication between the dentate nucleus and the cerebellar cortex. Small local circuit neurons include signaling pathways that are contained within the dentate. These neurons provide feedback to the dentate and allow for fine control of signaling. Currently, less research has been conducted on the specific shape and role of these neurons, as the dentate nucleus is composed primarily of large principal neurons.