Neural Anatomy - Quantitative Neurophysiology - page 6

that allow the brain to sense the concentrations of hormones in the blood. The downside of the blood
brain barrier is that it is difficult to design drugs that will work directly on the brain.
1.3.4 Directions in the Brain
Directions in the brain are the same as in the body. Anterior refers to the front of the brain while posterior
is toward the back. Medial is toward the center of the brain while lateral is away from the center. Superior
(also dorsal) is toward the top of the brain while interior (also ventral) is toward the base of the brain.
Two additional terms are used in the brain that trace a curved line from the bottom of the spinal
cord to the nose (or frontal lobe). Moving in a rostral direction is moving toward the nose. Moving in a
caudal direction is moving toward the bottom of the spinal cord.
1.3.5 Inputs and Outputs
The focus of the text is on neurons in the central nervous system. The mathematical models, however,
apply equally well to neurons in the peripheral nervous system. We therefore briefly mention that the
brain interacts with neurons in the body. Neural inputs to the brain typically originate from sensory
systems. Neurons that carry impulses to the brain are called afferent , sensory or receptor nerves. Typically,
these nerves originate in a sensory system such as the eyes or nose. Neurons that carry impulses away from
the brain are called efferent , motor or effector nerves. Typically, they will innervate muscles or glands.