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Encyclopedia > Central gray stratum
Brain: Periaqueductal gray
Section through superior colliculus showing path of oculomotor nerve. (Periaqueductal gray visible but not labeled.)
Coronal section through mid-brain.
1. Corpora quadrigemina.
2. Cerebral aqueduct.
3. Central gray stratum.
4. Interpeduncular space.
5. Sulcus lateralis.
6. Substantia nigra.
7. Red nucleus of tegmentum.
8. Oculomotor nerve, with 8’, its nucleus of origin. a. Lemniscus (in blue) with a’ the medial lemniscus and a" the lateral lemniscus. b. Medial longitudinal fasciculus. c. Raphé. d. Temporopontine fibers. e. Portion of medial lemniscus, which runs to the lentiform nucleus and insula. f. Cerebrospinal fibers. g. Frontopontine fibers.
Latin s. grisea centralis
Gray's subject #188 806
NeuroNames hier-501
MeSH Periaqueductal+Gray
Dorlands/Elsevier s_27/12766787

Periaqueductal gray (PAG; also called the "central gray") is the midbrain grey matter that is located around the cerebral aqueduct within the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour. The ascending pain and temperature fibers of the spinothalamic tract also send information to the PAG via the spinomesencephalic tract. The spinomesencephalic tract is so-named because the fibers orginate in the spine and terminate in the mesencephalon, another name for the midbrain, which is the part of the brain in which the PAG resides. Image File history File links Cn3nucleus. ... The superior colliculus is part of the brain that sits below the thalamus and surrounds the pineal gland in the mesencephalon of vertebrate brains. ... The oculomotor nerve () is the third of twelve paired cranial nerves. ... Image File history File links Gray710. ... In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ... Corpora quadrigemina (Latin: four twins) is the collective name given to both pairs of the inferior and superior colliculi. ... The mesencephalic duct, also known as the aqueduct of Sylvius or the cerebral aqueduct, contains cerebrospinal fluid (CSF), is within the mesencephalon (or midbrain) and connects the third ventricle in the diencephalon to the fourth ventricle, which is between the pons and cerebellum. ... The lateral sulcus (also called Sylvian fissure or lateral fissure) is one of the most prominent structures of the human brain. ... The substantia nigra, (Latin for black substance, Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system. ... The red nucleus is a structure in the rostral midbrain involved in motor coordination. ... The midbrain tegmentum is part of the midbrain extending from the substantia nigra to the cerebral aqueduct. ... The oculomotor nerve () is the third of twelve paired cranial nerves. ... This article needs to be wikified. ... The medial lemniscus, also known as Reils band or Reils ribbon, is a pathway in the brainstem that carries sensory information from the gracile and cuneate nuclei to the thalamus. ... The lateral lemniscus is a tract of axons in the brainstem that carries information about sound to the inferior colliculus of the midbrain. ... The medial longitudinal fasciculus (MLF) is a group of axons on each side of the brainstem, that carry information about the direction that the eyes should move. ... In general, a raphe (pronounced RAY-fee) is a seam. ... In the human nervous system the temporopontine fibers are lateral to the cerebrospinal fibers; they originate in the temporal lobe and end in the nuclei pontis. ... The medial lemniscus, also known as Reils band or Reils ribbon, is a pathway in the brainstem that carries sensory information from the gracile and cuneate nuclei to the thalamus. ... The lentiform nucleus or lenticular nucleus describes the putamen and the globus pallidus within the basal ganglia. ... Insula is the Latin word for island. It has other meanings: A Roman building with several stories. ... The cerebrospinal fibers, derived from the cells of the motor area of the cerebral cortex, occupy the middle three-fifths of the base; they are continued partly to the nuclei of the motor cranial nerves, but mainly into the pyramids of the medulla oblongata. ... The frontopontine fibers are situated in the medial fifth of the base of the cerebral peduncles; they arise from the cells of the frontal lobe and end in the nuclei of the pons. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... NeuroNames is a system of nomenclature for the brain and related structures. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Elseviers logo. ... In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ... Grey matter is a major component of the central nervous system, consisting of nerve cell bodies and short nerve cell extensions/processes (axons and dendrites). ... The mesencephalic duct, also known as the aqueduct of Sylvius or the cerebral aqueduct, contains cerebrospinal fluid (CSF), is within the mesencephalon (or midbrain) and connects the third ventricle in the diencephalon to the fourth ventricle, which is between the pons and cerebellum. ... In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ... Hurting redirects here. ... The spinothalamic tract is the sensory pathway in the body that transmits pain, temperature, itch and crude touch. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ...

Contents

Role in analgesia

Stimulation of the periaqueductal gray matter of the midbrain results in release of serotonin in the dorsal horn of the spinal cord, profound analgesia, activation of interneurons containing enkephalin, and release of norepinephrine (also known as noradrenaline) in the dorsal horn of the spinal cord. Serotonin (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and enterochromaffin cells in the gastrointestinal tract of animals including humans. ... The Spinal cord nested in the vertebral column. ... For other uses of painkiller, see painkiller (disambiguation) An analgesic (colloquially known as painkiller) is any member of the diverse group of drugs used to relieve pain. ... Endorphins are endogenous opioid biochemical compounds. ... Norepinephrine (INN) or noradrenaline (BAN) is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ... Norepinephrine, known as noradrenaline outside the USA, is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ...


Role in defensive behavior

Stimulation of the dorsal and lateral aspects of the PAG [in the rat] can provoke defensive responses characterised by freezing, running, jumping, tachycardia and increases in blood pressure and muscle tonus. Conversely, stimulation of the caudal ventrolateral PAG can result in an immobile, relaxed posture known as quiescence. In physics and chemistry, freezing is the process of cooling a liquid to the temperature (called freezing point) where it turns into a solid. ... In cell biology, quiescence is the state of a cell when it is not dividing. ...


Lesions of the caudal ventrolateral PAG can greatly reduce conditioned freezing, while lesions of the dorsal aspect can reduce innate defensive behavior, virtually "taming" the animal. Classical conditioning (also Pavlovian conditioning, respondent conditioning or alpha-conditioning) is a type of associative learning. ...


Role in reproductive behavior

Neurons of the PAG are excited by endorphins and by opiate analgesics. It also plays a role in female copulatory behavior (see Lordosis behavior) via a pathway from the ventromedial nucleus of the hypothalamus. Drawing by Santiago Ramón y Cajal of neurons in the pigeon cerebellum. ... Endorphins are endogenous opioid biochemical compounds. ... In medicine, the term opiate describes any of the narcotic alkaloids found in opium. ... This article or section does not adequately cite its references or sources. ... This article or section does not cite any references or sources. ... Lordosis behavior is a sexual response during estrus in certain female animals, such as mice and cats, that consists of a downwards arching of the spine. ... The hypothalamus, also known as the master gland, links the nervous system to the endocrine system via the pituitary gland. ...


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