A genetically defined pontine nucleus essential for ingestion in mice.

The first phase of feeding consists in the procurement of solid foods from the environment by biting, and their preparation for swallowing by chewing. These actions require the precise coordination of tens of orofacial muscles for the jaw and tongue. The seat for this motor patterning is known to reside in the reticular formation, a complex and poorly mapped region of the hindbrain, but the neuron groups involved are still elusive.

The pelvic organs receive no parasympathetic innervation.

The pelvic organs (bladder, rectum, and sex organs) have been represented for a century as receiving autonomic innervation from two pathways - lumbar sympathetic and sacral parasympathetic - by way of a shared relay, the pelvic ganglion, conceived as an assemblage of sympathetic and parasympathetic neurons. Using single-cell RNA sequencing, we find that the mouse pelvic ganglion is made of four classes of neurons, distinct from both sympathetic and parasympathetic ones, albeit with a kinship to the former, but not the latter, through a complex genetic signature. We also show that spinal lumbar preganglionic neurons synapse in the pelvic ganglion onto equal numbers of noradrenergic and cholinergic cells, both of which therefore serve as sympathetic relays.

A medullary centre for lapping in mice.

It has long been known that orofacial movements for feeding can be triggered, coordinated, and often rhythmically organized at the level of the brainstem, without input from higher centers. We uncover two nuclei that can organize the movements for ingesting fluids in mice. These neuronal groups, IRt and Peri5, are marked by expression of the pan-autonomic homeobox gene Phox2b and are located, respectively, in the intermediate reticular formation of the medulla and around the motor nucleus of the trigeminal nerve.

Taste bud formation depends on taste nerves.

It has been known for more than a century that, in adult vertebrates, the maintenance of taste buds depends on their afferent nerves. However, the initial formation of taste buds is proposed to be nerve-independent in amphibians, and evidence to the contrary in mammals has been endlessly debated, mostly due to indirect and incomplete means to impede innervation during the protracted perinatal period of taste bud differentiation. Here, by genetically ablating, in mice, all somatic (i.

Dual origin of enteric neurons in vagal Schwann cell precursors and the sympathetic neural crest.

Most of the enteric nervous system derives from the "vagal" neural crest, lying at the level of somites 1-7, which invades the digestive tract rostro-caudally from the foregut to the hindgut. Little is known about the initial phase of this colonization, which brings enteric precursors into the foregut. Here we show that the "vagal crest" subsumes two populations of enteric precursors with contrasted origins, initial modes of migration, and destinations.

Ancient origin of somatic and visceral neurons.

Background: A key to understanding the evolution of the nervous system on a large phylogenetic scale is the identification of homologous neuronal types. Here, we focus this search on the sensory and motor neurons of bilaterians, exploiting their well-defined molecular signatures in vertebrates. Sensorimotor circuits in vertebrates are of two types: somatic (that sense the environment and respond by shaping bodily motions) and visceral (that sense the interior milieu and respond by regulating vital functions).

Centralization of the deuterostome nervous system predates chordates.

The origin of the chordate central nervous system (CNS) is unknown. One theory is that a CNS was present in the first bilaterian and that it gave rise to both the ventral cord of protostomes and the dorsal cord of deuterostomes. Another theory proposes that the chordate CNS arose by a dramatic process of dorsalization and internalization from a diffuse nerve net coextensive with the skin of the animal, such as enteropneust worms (Hemichordata, Ambulacraria) are supposed to have.

Precraniate origin of cranial motoneurons.

The craniate head is innervated by cranial sensory and motor neurons. Cranial sensory neurons stem from the neurogenic placodes and neural crest and are seen as evolutionary innovations crucial in fulfilling the feeding and respiratory needs of the craniate "new head." In contrast, cranial motoneurons that are located in the hindbrain and motorize the head have an unclear phylogenetic status.

The differentially expressed C21orf5 gene in the medial temporal-lobe system could play a role in mental retardation in Down syndrome and transgenic mice.

Mental retardation represents the more invalidating pathological aspect of Down syndrome, DS, and has a hard impact in public health. Modifications in DS brain, concerning abnormal size, neuronal differentiation, and cell density, cause changes in the neurophysiology and behavior of DS patients, and could be determined by dosage imbalance of genes localized in the DS critical region, DCR. Among these genes, C21orf5 showed high homology with Caenorhabditis elegans Pad1 involved in cellular differentiation and patterning.