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Ascending reticular activating system. Reticular formation labeled near center. The ascending reticular activating system (ARAS), also known as the extrathalamic control modulatory system or simply the reticular activating system (RAS), is a set of connected nuclei in the brains of vertebrates that is responsible for regulating wakefulness and ...
The pedunculopontine nucleus (PPN) or pedunculopontine tegmental nucleus (PPT or PPTg) is a collection of neurons located in the upper pons in the brainstem. [1] [2] It is involved in voluntary movements, [3] arousal, and provides sensory feedback to the cerebral cortex and one of the main components of the ascending reticular activating system.
Arousal is the physiological and psychological state of being awoken or of sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the brain, which mediates wakefulness, the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, desire ...
It is a part of the reticular activating system in the reticular formation. [ 3 ] The locus coeruleus, which in Latin means "blue spot", is the principal site for brain synthesis of norepinephrine (noradrenaline).
One such example is the heterogeneous collection of more than two dozen nuclei on each side of the upper brainstem (pons, midbrain and in the posterior hypothalamus), collectively referred to as the reticular activating system (RAS). Their axons project widely throughout the brain.
Giuseppe Moruzzi (July 30, 1910 – March 11, 1986) was an Italian neurophysiologist. He was one of three scientists who connected wakefulness to a series of brain structures known as the reticular activating system, and his work reframed sleep as an active process in the brain rather than a passive one.
The subparabrachial nucleus (also known as the Kölliker-Fuse nucleus, or diffuse reticular 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 .
By projecting to the reticular activating system (RAS), the tract also mediates arousal/alertness (including wakefulness) in response to noxious (harmful) stimuli. The tract is phylogenetically older than the spinothalamic ("neospinothalamic") tract.