Asked by: Lorenzo Metais
medical health brain and nervous system disorders

What is periaqueductal gray matter?

Last Updated: 25th January, 2020

The periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It projects to the nucleus raphe magnus, and also contains descending autonomic tracts. This region has been used as the target for brain-stimulating implants in patients with chronic pain.

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Also to know is, what is the function of periaqueductal gray of the brainstem?

The periaqueductal gray (PAG) is an anatomic and functional interface between the forebrain and the lower brainstem and has a major role in integrated behavioral responses to internal (e.g., pain) or external (e.g., threat) stressors.

One may also ask, what is the PAG in the brain? The periaqueductal gray, or PAG, is an area of gray matter found in the midbrain. The PAG surrounds the cerebral aqueduct (hence the name periaqueductal) and occupies a column of brainstem that stretches about 14 mm long.

Likewise, people ask, what does periaqueductal mean?

Medical Definition of periaqueductal : of, relating to, or being the gray matter which surrounds the aqueduct of Sylvius.

What is the descending pain pathway?

The circuit that consists of the periaqueductal gray (PAG) matter in the upper brain stem, the locus coeruleus (LC), the nucleus raphe magnus (NRM) and the nucleus reticularis gigantocellularis (Rgc) contributes to the descending pain suppression pathway, which inhibits incoming pain information at the spinal cord

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What is PAG in medical terms?

Anatomical terms of neuroanatomy
The periaqueductal gray (PAG, also known as the central gray) is a nucleus that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for descending pain modulation.

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Where is the substantia Gelatinosa located?

Substantia gelatinosa is a collection of cells in the gray area (dorsal horns) of the spinal cord. Found at all levels of the cord, it receives direct input from the dorsal (sensory) nerve roots, especially those fibers from pain and thermoreceptors.

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What does the reticular formation do?

Sleep and consciousness – The reticular formation has projections to the thalamus and cerebral cortex that allow it to exert some control over which sensory signals reach the cerebrum and come to our conscious attention. It plays a central role in states of consciousness like alertness and sleep.

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What is the red nucleus?

The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin.

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Which of the following grooves separates the cerebrum from the cerebellum?

The longitudinal fissure separates the two cerebral hemispheres and the transverse fissure is what separates the cerebrum from the cerebellum. Utilizing your knowledge of the brain model, identify the frontal, parietal, temporal, and occipital lobes of the cerebrum.

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What is stress induced analgesia?

Introduction. Stress-induced analgesia (SIA) is an in-built mammalian pain suppression response that occurs during or following exposure to a stressful or fearful stimulus.

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In what part of the brain would you find the cerebral aqueduct?

The cerebral aqueduct (aqueductus mesencephali, mesencephalic duct, sylvian aqueduct or aqueduct of Sylvius) is within the midbrain. It contains cerebrospinal fluid (CSF) and connects the third ventricle to the fourth ventricle, located dorsal to the pons and ventral to the cerebellum.

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What is neuropathy pain?

Neuropathic pain is often described as a shooting or burning pain. It can go away on its own but is often chronic. Sometimes it is unrelenting and severe, and sometimes it comes and goes. It often is the result of nerve damage or a malfunctioning nervous system.

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What is pain made of?

When we feel pain, such as when we touch a hot stove, sensory receptors in our skin send a message via nerve fibres (A-delta fibres and C fibres) to the spinal cord and brainstem and then onto the brain where the sensation of pain is registered, the information is processed and the pain is perceived.

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What are the two pain pathways to the brain?

There are two main pathways that carry nociceptive signals to higher centres in the brain. The spinothalamic tract: secondary afferent neurones decussate within a few segments of the level of entry into the spinal cord and ascend in the contralateral spinothalamic tract to nuclei within the thalamus.

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What are the four phases of of the pain pathway?

Nociceptive pain occurs in 5 phases: 1) Transduction, 2) Conduction, 3) Transmission, 4) Modulation, 5) Perception. Transduction begins when peripheral terminals of nociceptive C fibers and A-delta (Aδ) fibers are depolarized by noxious mechanical, thermal, or chemical energy.

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What is a descending tract?

The descending tracts are the pathways by which motor signals are sent from the brain to lower motor neurones. The lower motor neurones then directly innervate muscles to produce movement. Pyramidal tracts – These tracts originate in the cerebral cortex, carrying motor fibres to the spinal cord and brain stem.

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Which nerves carry pain information to the brain?

Somatosensory neurons (and pain receptors all over the face and head) travel into the central nervous system through the trigeminal nerve.

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What is endogenous pain?

Concept. Endogenous pain modulation is a wide-ranging term, delineating the array of actions that the central nervous system can use to reduce, or, at times, augment pain.

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How pain is interpreted by the brain?

The Role of the Brain in Interpreting Pain
When the pain signal reaches the brain it goes to the thalamus, which directs it to a few different areas for interpretations. Signals are also sent from the thalamus to the limbic system, which is the emotional center of the brain.

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What are the ascending pathways?

Ascending pathway: A nerve pathway that goes upward from the spinal cord toward the brain carrying sensory information from the body to the brain. In contrast, descending pathways are nerve pathways that go down the spinal cord and allow the brain to control movement of the body below the head.