A major theme of the systems physiologists is the critical timing function of the cerebellum. However, the biophysicists do not appear to directly address the biophysical basis of the adaptive timing competence implicated in the physiological and behavioral data. Thus, the bridge between the macroscopic and microscopic data bases seems to be incomplete in a critical area. We report successful results from an attempt to add the missing part of the bridge. It comes in the form of a model of (...) how the second messenger system activated by parallel fiber inputs - the mGluR channel - can literally bridge the temporal gap between CS and CR, both in standard conditioning tasks and more generally, [CRÉPEL et al.; HOUK et al.; KANO; LINDEN; SIMPSON et al.; SMITH; THACH; VINCENT]. (shrink)