Lateralized Memory Storage and Crossed Inhibition During Odor Processing by Limax

After odor conditioning intact Limax maximus and injecting Lucifer yellow (LY) into their haemocoel, LY labeled groups of neurons are found in either the right or left procerebral (PC) lobe but never in both PC lobes. This suggests that a competitive interaction occurs between right and left odor processing pathways of which the PC lobe is a part. We use the nerve discharge in the external peritentacular nerve (ePTN) evoked by applying a puff of conditioned odor to the nose to document crossed inhibition between left and right odor processing pathways. Responses in the ePTN evoked by stimulating one superior nose with a conditioned odor are strongly lateralized as responses occur only on the stimulated side. Stimulating both superior noses simultaneously with the same conditioned odor yields responses in both ePTNs that resemble the sum of responses to unilateral stimulation. Simultaneously stimulating both superior noses, each with a different conditioned odor, leads to strong inhibition of both ePTN responses. The crossed inhibition is also evident if both superior and inferior noses on the same side are stimulated simultaneously. A lateral inhibitory mechanism, situated postsynaptic to odor recognition, appears to inhibit ePTN responses if the two noses receive conflicting sensory inputs.