The Basal Ganglia Underpinning of Cognitive Control: The Fronto-Striatal System

Abstract

The organization of the cortex includes widespread connections with the basal ganglia. The basal ganglia are a group of subcortical nuclei that are bilaterally represented within the brain. These nuclei consist of the striatum (a general term that includes the caudate, the putamen, and the ventral striatum/nucleus accumbens), the globus pallidus (which is divided into two separate compartments called the external and internal segments), and the subthalamic nucleus and substantia nigra (which can be further divided into the substantia nigra pars reticulata and the substantia nigra pars compacta). The striatum is divided and referred to by its dorsal and ventral components; the subdivisions of the globus pallidus are referred to as the Gpe and Gpi, according to its two compartments; the subthalamic nucleus is referred to as the STN, and the organization of the substantia nigra complex often follows the abbreviations SNr and SNpc. These are phylogenetically old regions of the vertebrate brain, these regions have very similar anatomic and neurochemical profiles across species, and they are believed to serve the same functions in all vertebrates [234–237]. In fact, the structure and function of the basal ganglia have been conserved over some 560 million years of evolution [238]. Therefore, the argument concerning the role of the basal ganglia presented in this paper certainly has a compelling history on its side. You simply cannot have a vertebrate brain without the basal ganglia. (This paper assumes the reader has a fundamental knowledge of the basal ganglia; reviews are provided by [1, 46, 239, 240]; the following information provides only a minimal, elementary summary of basal ganglia structure and function.)