The hippocampus is involved with putting memories into permanent storage. Hippocampus is a large limbic system structure that has been implicated in learning and memory. Removal of the hippocampus in humans (as was done years ago to treat epilepsy) causes amnesia. In rats, the hippocampus is important for spatial memory, and removal of hippocampus will prevent an animal from learning even a very simple maze consisting of an open field with no walls. Most drugs have effects on the hippocampus. The drug effects on the hippocampus may be related to state dependency and long-term effects rather than acute effects.
Peripheral Nervous System (PNS) is divides into two functional units: Somatic and Autonomic nervous system. The autonomic nervous system also has two parts; the parasympathetic Synapse xt nervous system, which controls the vegetative involuntary functions of the body on an ongoing basis, and the sympathetic nervous system, which prepares the body sudden expenditure of energy, the fight-or-flight response. Somatic nervous system made up of all of the sensory nerves running from the sensory receptors in the eyes, ears, and skin to the CNS. Somatic nervous system also contains the motor nerves. Somatic system is a voluntary control
Reticular Activating System (RAS) Surround the medulla. RAS is a complicated interconnection of diffuse centers and branching fiber tracts connected in such a way that when one part is excited, the entire system becomes activated. Two diffuse projection systems originated in the medulla and run forward into the higher parts of the brain: the reticular activating system (RAS) and the Raphe’ system.