Parabrachial nuclei

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Parabrachial nuclei

Details

Part of

Brainstem

Parts

Medial parabrachial nucleus,?Lateral parabrachial nucleus,?Subparabrachial nucleus

Identifiers

Latin

nuclei parabrachiales

MeSH

D065823

NeuroNames

1927

NeuroLex?ID

nlx_23647

TA98

A14.1.05.439

TA2

5945

FMA

84024

Anatomical terms of neuroanatomy

[edit on Wikidata]

The?parabrachial nuclei, also known as the?parabrachial complex, are a group of?nuclei?in the dorsolateral?pons?that surrounds the?superior cerebellar peduncle?as it enters the?brainstem?from the?cerebellum. They are named from the Latin term for the superior cerebellar peduncle, the?brachium conjunctivum. In the?human brain, the expansion of the superior cerebellar peduncle expands the parabrachial nuclei, which?form a thin strip of?grey matter?over most of the peduncle. The parabrachial nuclei are typically divided along the lines suggested by Baxter and Olszewski in humans, into a medial parabrachial nucleus and lateral parabrachial nucleus.[1]?These have in turn been subdivided into a dozen subnuclei: the superior, dorsal, ventral, internal, external and extreme lateral subnuclei; the lateral crescent and subparabrachial nucleus (Kolliker-Fuse nucleus) along the ventrolateral margin of the lateral parabrachial complex; and the medial and external medial subnuclei[2][3]

Contents

·?1Components

·?2Function

·?2.1Arousal

·?2.2Blood sugar control

·?2.3Thermoregulation

·?2.4Taste

·?2.5Pleasure

·?3References

Components[edit]

The main parabrachial nuclei are the medial parabrachial nucleus, the lateral parabrachial nucleus and the subparabrachial nucleus.

The?medial parabrachial nucleus?is one of the three main?nuclei?in the parabrachial area at the junction of the?midbrain?and the?pons. It relays information from the taste area of the?solitary nucleus?to the?ventral posteromedial nucleus?of the?thalamus.[4]

The?lateral parabrachial nucleus?is one of three main parabrachial nuclei, located at the junction of the?midbrain?and pons. It receives information from the?caudal?solitary tract?and transmits signals mainly to the?medial?hypothalamus?but also to the lateral?hypothalamus?and many of the nuclei targeted by the medial parabrachial nucleus.[4]

The?subparabrachial nucleus, also known as the?K?lliker-Fuse nucleus?and?diffuse reticular nucleus, is one of the three parabrachial nuclei between the?midbrain?and the?pons. The subparabrachial nucleus regulates the?breathing rate.?It receives signals from the?caudal, cardio-respiratory part of the?solitary nucleus?and sends signals to the lower?medulla oblongata, the?spinal cord, the?amygdala?and the?lateral?hypothalamus.[4]

The parabrachial nuclei receive?visceral afferent?information from a variety of sources in the brainstem, including much input from the?solitary nucleus, which brings?taste?information and information about the remainder of the body.[5]?The external, dorsal, internal and superior lateral subnuclei also receive input from the spinal and trigeminal dorsal horn, mainly concerned with pain and other visceral sensations.[6]?Outputs from the parabrachial nucleus originate from specific subnuclei and target forebrain sites involved in autonomic regulation, including the lateral hypothalamic area, ventromedial, dorsomedial, and arcuate hypothalamic nuclei, the median and lateral preoptic nuclei, the substantia innominate, the ventroposterior parvicellular and?intralaminar thalamic nuclei, the central nucleus of the amygdala, and the insular and infralimbic cortex.[2]?The subparabrachialnucleus and lateral crescent send efferents to the nucleus of the solitary tract,?ventrolateral medulla, and spinal cord, where they target many respiratory and autonomic cell groups.[3]?Many of these same brainstem and forebrain areas send efferents back to the parabrachial nucleus as well.[7][5]

Function[edit]

?

This section?needs expansion.?You can help by?adding to it.(April 2016)

Arousal[edit]

Further information:?Ascending reticular activating system

Many subsets of neurons in the parabrachial complex that target specific?forebrain?or brainstem cell groups contain specific?neuropeptides,[8]?and appear to carry out distinct functions. For example, a population of neurons in the external lateral parabrachial subnucleus that contain the neurotransmitter?calcitonin gene-related peptide?(CGRP) appears to be critical for relaying information about?hypoxia?or?hypercapnia?(e.g., if one is being suffocated during sleep, such as by?sleep apnea) to forebrain sites to wake up the brain, and prevent?asphyxia.[9]

Recent data indicate that?glutamatergic?neurons in the medial and lateral parabrachial nuclei, along with glutamatergic neurons in the?pedunculopontine tegmental nucleus, provide a critical node in the brainstem for producing a?waking state.[10][11]Lesions of these neurons cause irreversible?coma.

Blood sugar control[edit]

Other neurons in the superior lateral parabrachial nucleus that contain cholecystokinin have been found to prevent hypoglycemia.[12]

Thermoregulation[edit]

Other neurons in the dorsal lateral parabrachial nucleus that contain?dynorphin?sense?skin?temperature from spinal afferents, and send that information to neurons in the?preoptic area?involved in?thermoregulation.[13]?A study in 2017, has shown this information to be relayed through the lateral parabrachial nucleus rather than the thalamus, which drives thermoregulatory behaviour.[14][15]

Taste[edit]

Parabrachial neurons in rodents that relay taste information to the?ventroposterior parvocellular?(taste) nucleus of the?thalamus?are mainly CGRP neurons in the external medial parabrachial nucleus and they project predominantly?contralaterally, as well as a smaller number in the ventral lateral nucleus, which project mainly?ipsilaterally.[16]

Neurons that mediate the sensation of?itching, connect to the parabrachial nucleus by way of glutamatergic spinal projection neurons. This pathway triggers scratching in mice.[17]

Pleasure[edit]

The parabrachial nucleus relays satiety and pain-related signals to higher brain regions; when inhibited, this can produce "liking" responses to certain?pleasurable stimuli, such as sweet taste.[18]