Reticular Activating System
The RAS refers to a network of nerves and connections that originate in the superior portion of the brainstem which together serve the purpose of modulating attention and arousal .
The RAS, also known as the reticular formation, refers to a network of nuclei and fibers that extend throughout the central portion of the brainstem from the medulla to the midbrain [1, 2]. While the RAS is described as the primary source/ site of brain activation (e.g. ), this is just one portion of the functional role the RAS plays. The superior portion of the RAS, which is based in the upper pons and extends into the midbrain, regulates arousal level and consciousness . In contrast, the inferior portion of the RAS, which lies in the lower pons and medulla, tends to be primarily involved in motor and autonomic function .
Due to its direct and indirect connections throughout the system, lesions of the RAS...
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