<prompt> The reticular formation is a diffuse collection ofOnly motor neuronsOnly sensory neuronsOnly autonomic centresAll of the above  <response>: D All of the above Reticular formation, the phylogenetically old reticular core of the brain, occupies the midventral portion of the medulla and midbrain. It is primarily an anatomic area made up of various neural clusters and fibers with discrete functions. It contains the cell bodies and fibers of many of the serotonergic, noradrenergic, and adrenergic systems. It also contains many of the areas concerned with regulation of heart rate, blood pressure and respiration The RAS is a complex polysynaptic pathway. 