Interaction of periodontal and jaw elevator spindle afferents in the cerebellum--sensory calibration.

Electrical stimulation of low threshold, fast afferents in the inferior alveolar nerve produce very short latency synaptic field potentials in the cerebellar cortex anterior lobe typical of mossy fibre inputs. The afferents concerned are from periodontal receptors, some of which project directly without relay. Muscle afferents do not show this direct projection. The functional significance of this arrangement is discussed, bearing in mind the parallel with the direct projection of some first order vestibular afferents. It is suggested that the specialisation seen may be the basis for sensory calibration of spindle inputs by means of periodontal afferents.