Synaptic connections of Purkinje cell axons with nucleocortical neurones in the cerebellar medial nucleus of the rat

Abstract

The cerebellar nucleocortical neurones may be part of a cortico-nucleocortical loop. It has not yet been demonstrated, however, whether they are directly afferented by Purkinje cell axons. This question has been addressed by using electron microscopic methods. WGA-HRP injections into the cerebellar vermis anterogradely labelled Purkinje cell terminals and retrogradely labelled nucleocortical neurones of the nucleus medialis. Postembedding GABA immunolabelling was used to double-labelled PC terminals and identified the GABA-immunoreactive nuclear neurones. Of the identified nucleocortical neurones, the majority were immunonegative, but a few were GABA-immunoreactive. Both types were in synaptic contact with identified Purkinje cell terminals.