Inhibitory action of glutamic acid on cerebellar interneurones

GLUTAMIC acid strongly excites almost all central neurones examined, and it has been considered to be a main excitatory transmitter in the mammalian brain1,2. Although some neurones in the olfactory bulb have been inhibited by glutamic acid3, this has been explained by the assumption that glutamate primarily activated γ-aminobutyrate (GABA)-releasing inhibitory interneurones, which in turn inhibited the neurones in question1. In the experiments reported here, glutamate inhibited neurones in the granular layer of the cerebellum: this action does not seem to be mediated by inhibitory interneurones.