Olfactory inputs to a bursting serotonergic interneuron in a terrestrial mollusc

Olfactory fiber tracts in Limax maximus Linnaeus terminate in the cerebral ganglion, and arborize near the metacerebral giant cell (MGC). In the preparation herein described the serotonergic MGC fires in bursts. Electrical stimulation of an olfactory nerve (OfN) elicits complex postsynaptic potentials (PSPs) in the ipsilateral MGC that disrupt its bursting. Rigidly controlled stimulation of a nose with natural or synthetic odors elicits a brief burst of compound action potentials in the ipsilateral OfN (en passant recording). Olfactory stimulation of a nose leads to PSPs in the ipsilateral MGC which can cause an increase in its firing rate and alter the firing pattern of the contralateral MGC. Olfactory stimulation failed to activate the feeding neural network of which the MGC is part. MGC bursting is discussed.