INFORMATIONAL ANALYSIS OF THE BASAL GANGL IA RELATED SYSTEM

This paper describes a major cerebral system whose contours are only e merging: the ''basal ganglia related system''. This is made up of the ''system of the basal ganglia'' itself plus its inputs and outputs. Th e system of rile basal ganglia may be divided into the ''basal ganglia core'' comprising the striatum and its pallidal and nigral targets an d the ''regulators of the core''. Distinguishable include regulators o f the striatum (the dopaminergic pars compacta and the central complex of the thalamus or centre median-parafascicularis), regulators of the pallidonigrum (the subthalamic nucleus and the pedunculopontine compl ex) and internal regulators (at first the lateral nucleus of the palli dum). The main input to this system comes from the cerebral cortex. Th e main output is the thalamus and from it to the cortex. The whole ''b asal ganglia related system'' may thus be seen as a cortico-cortical c ircuit passing through the basal ganglia. Information processing in th e system is very complex. New data presented here emphasize two connec tions: cortico-striate and striato-pallidonigral connections. It is st ressed that the first uses complex combinations of confluence or diflu ence on small matricial islands. This step could be a selection and re organisation of cortical information. The second process is a strong ' 'dynamically focused convergence'' combining information from differen t upstream sources in order to derive an adequate informational produc t for the production of harmonious and adaptated matricity.