Several models have been elaborated to describe the structure and function of the basal ganglia, but its different levels of architectural organization, macroscopic anatomy, connectivity, functional territorial subdivision and neuronal morphology have rarely been considered. In this review, I present some of these models and I analyze the functioning of the basal ganglia at the light of its architectural properties.

The basal ganglia form an important neuronal system, which interacts with the cerebral cortex through a complex series of loop circuits. While the morphological, electrophysiological and biochemical properties of this system are progressively known better and better, they have led to various interpretations from which different, sometimes contradictory, models have been constructed. The basal ganglia are often analyzed as homogeneous nuclei that communicate through excitatory or inhibitory connections, the so-called “box and arrows” models. Among them, the dual-, triple- and five circuit models are the most popular. Analysis of the “inside of the boxes” provides, however, important data such as the functional subdivision into three, motor, associative and limbic territories and the demonstration that integrative properties are a characteristic of the basal ganglia.

Considering these properties, the way cortical information is processed in the basal ganglia can be analyzed, which leads to modeling its organization and functioning. The striatum receives a compressed version of cortical information and transforms it through complex processes of activation/deactivation under a double dopaminergic and cholinergic control that enables behavioral reinforcement learning. The globus pallidus behaves as a keyboard on which various behavioral repertoires can be coded, from the simplest movement of a single joint to the most complex motor sequence involving the entire body and expressing an emotional content in a cognitive context. The role of the subthalamic nucleus must be considered at different scales. At the macroscopic scale, it works as a thermostat that regulates the level of execution of cortical commands. At a territorial scale, it can process separately motor, cognitive and emotional information. At the neuronal scale, it assures a much finer neuronal representation of cortical commands and can integrate motor, cognitive and emotional aspects. New experiments in both animal models and human clinical-research protocols are needed to demonstrate the neuronal mechanisms of these processes.

A model is proposed that considers how neural information is processed in the basal ganglia during the execution of motor, cognitive and emotional activities.

Différent modèles des ganglions de la base ont été élaborés, mais différents niveaux d’organisation sont rarement considérés.

Les ganglions de la base sont souvent analysés comme des noyaux homogènes qui communiquent par des connexions activatrices ou inhibitrices, les modèles « boîtes–flèches ». L’analyse de « l’intérieur de la boîte » apporte cependant des données importantes, comme la subdivision en territoires fonctionnels et la démonstration de propriétés intégratives.

Partant de ces propriétés, la façon dont l’information est traitée peut être analysée. Le striatum reçoit une version compressée de l’information corticale et la transforme selon un processus d’apprentissage comportemental renforcé par la dopamine et l’acétylcholine. Le pallidum se comporte comme un clavier sur lequel le répertoire comportemental peut être codé, du simple mouvement d’une articulation à une séquence complexe impliquant le corps entier et un contenu émotionnel et cognitif. Le noyau subthalamique se comporte comme un thermostat qui régule le niveau d’exécution de la commande corticale, mais il en assure aussi une représentation plus fine qui intègre ses aspects moteur, cognitif et émotionnels.

Un modèle est proposé qui considère le traitement de l’information dans les ganglions de la base pendant l’exécution d’activités motrices, cognitives et émotionnelles.