[Cerebellar cortex: simulation of recurrent collateral inhibition with the aid of a set of neuronal automata. I. Model and global results].

In view of a study on the transfer function of the cerebellar cortex a modelization of each of the various subsystems was undertaken. The recurrent collateral inhibition existing between Purkinje cells was mimicked by means of an assembly of neuronal automata (NA) temporally evolving at random through three states ("silent", "tonic" and "phasic" and interacting with simple rules. In such an assembly--by comparison with a control group of independent NA--a drastic modulation of activity appears. First the total of the mean number of state shifts is increased by more than 10%. This increase is clearly hierarchical with a maximal effect for the "silent" state. Second the average duration of each state also varies, although in a contrasted manner. Third, and moreover, a clear spatial cooperativity emerges. Indeed all the individually coupled NA are in the same "silent" state at identical moments for more than 5.5% of the total running time. A cyclic repetition of this spatiotemporal cooperativity is apparent. The emergence of these collective properties--which can not be deduced linearly from the unitary elements--introduces a parameter of order leading to a coherent functioning of the system.