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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.
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).
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 ...
Its function is modulatory on signals going through the thalamus (and the reticular nucleus). The thalamic reticular nucleus receives massive projections from the external segment of the globus pallidus, thought to play a part in disinhibition of thalamic cells, which is essential for initiation of movement (Parent and Hazrati, 1995). [9]
The tract transmits slow nociceptive/pain information (but thermal, and crude touch information as well) from the spinal cord to reticular formation which in turn relays the information to the thalamus via reticulothalamic fibers as well as to other parts of the brain (as opposed to the spinothalamic tract - the direct pathway of the ...
The ascending reticular activating system consists of a set of neural subsystems that project from various thalamic nuclei and a number of dopaminergic, noradrenergic, serotonergic, histaminergic, cholinergic, and glutamatergic brain nuclei.
Here, a small image, e.g., a horizontal grating, is presented to the left eye, and another image, e.g., a vertical grating, is shown to the corresponding location in the right eye. In spite of the constant visual stimulus, observers consciously see the horizontal grating alternate every few seconds with the vertical one.