Chapter 7 - Subpallial Structures

Abstract

The subpallium is the major, basal subdivision of the embryonic telencephalon, and gives rise to centers that play key roles in the control of motor, cognitive, and emotional responses. These centers include: the basal ganglia, with striatal and pallidal parts; the centromedial extended amygdala; the corticopetal cell groups of the basal telencephalon; most of the septum; and the preoptic region, which represents the nonevaginated part of the telencephalon. Subpallial centers are considered an interface between the cerebral cortex and the effector centers of the hypothalamus and brainstem. However, the subpallium is much more than this, since it receives direct information on the external world and the internal body state, and plays a key role in executing, planning, and learning motivated behavior, as well as the direct control of basic functions essential for individual and species survival. Some subpallial centers have received special attention due to their involvement in devastating human diseases, such as: Huntington's disease caused by a neurodegeneration in the basal ganglia that leads to motor dysfunctions; or several neuropsychiatric disorders correlated to alterations in the corticopetal cell groups of the subpallium and/or the amygdala, which lead to cognitive impairments and/or social and emotional disorders. Due to its great complexity, many aspects of the cellular, anatomical and functional components and organization of the subpallium have remained obscure or controversial, confounding attempts to understand the pathophysiology of human diseases that involve subpallial structures. The mouse has become a very useful model for developmental and genetic studies in mammals, displacing the rat as the most important model of the mammalian brain. The comprehension of the subpallial basic units and their derivatives in the mouse is opening new venues for understanding its functional anatomy in the mature brain of mammals.