Dynamic and Plastic Properties of the Brain Stem Neuronal Networks as the Possible Neuronal Basis of Learning and Memory

It has long been believed that nerve connections in the brain are stable and rigid after their formation at an early developmental stage. However, although this rigidity of the nerve connections probably provides an important basis for instinctive behaviors, as the built-in generator of fixed action pattern, it cannot readily account for any kinds of adaptive behaviors, such as learning and memory. In this context it has recently been recognized that some of the nerve connections of the brain have plasticity. That is, they can be modified to some extent. This “plasticity” is thought to be the neural basis for adaptive behaviors. In other words, the “plasticity” and “rigidity” of the neural networks may relate to the environmental versus genetic factors which underlie behavior.