a. Visceral Centers of the Medulla. There is a group of nuclei in the medulla
of the hindbrainstem. Together, these nuclei control the visceral activities of the body,
such as respiration, heart beat, etc.
b. Reticular Formation. Within the substance of the brainstem is a diffuse
system called the reticular formation. The reticular formation has a facilitory (excitatory)
area and an inhibitory area. Thus, this control area tends to activate or slow down
activities of the body. Thus, it is responsible for producing sleep or wakefulness.
c. Hypothalamus and Thalamus.
(1) The thalamus is a group of nuclei found together in the forebrainstem.
The thalamus is the major relay center of sensory inputs from the body.
(2) The hypothalamus is a higher control center for visceral activities of the
body. It is found associated with the thalamus.
The cerebellum has been greatly developed, with many functional subdivisions.
It is the primary center for the integration and control of patterned, sequential motions of
the body. The cerebellum is also the center of control of body posture and equilibrium.
In humans, the highest level of nervous control is localized in the cerebrum. It is
at this level that conscious sensation and volitional motor activity are localized. Even
so, we can clearly designate three levels of control within the cerebrum:
a. Visceral (Vegetative) Level. This level is concerned primarily with visceral
activities of the body, as related to fight-or-flight, fear, and other emotions.
b. Patterned (Stereotyped) Motor Actions. Here, activities of the body are
standardized and repetitive in nature. An example of a stereotyped pattern of muscle
activity would be the sequence of muscle actions involved in walking.
c. Volitional Level. The volitional level is the highest and newest level of
control. Here, cognition (thinking) occurs, and unique, brand-new solutions can be