Homeostasis is the process by which the internal milieu of the body is able to maintain
equilibrium in the face of constant insults from the external world. Endocrine, immune, and
vascular systems play pivotal roles in adjusting internal biochemical reactions to counteract
assaults from the outside. Despite the vast accumulation of data over the last 50 years, a role
for serotonin in brain homeostasis has not been proposed. In this chapter I will review the
plasticity and anatomy of serotonergic neurons in integrating external sensory and motor …