In many species of snails and slugs, the receptor cells of the olfactory epithelia (located on the two optical tentacles) send axons through olfactory nerves to a pair of cerebral ganglia (Hubendick 1955).

Electrophysiological and imaging analyses have demonstrated that olfactory information processing and olfactory learning in many species of slugs and snails occurs in the procerebrum located at the point Inhibitors,research,lifescience,medical where the olfactory nerve joins the cerebral ganglion (Chase 1985; Gelperin and Tank 1990; this website Kimura et al. 1998; Straub et al. 2004; Ierusalimsky and Balaban 2010). The procerebrum consists of a layer of small, densely packed cell bodies and two separate layers of neuropil. The procerebrum shares several characteristics with the olfactory bulb of mammals, including large, spontaneous oscillations in the local field potential (Delaney et al. 1994) that are changed in frequency and amplitude by odor stimulation (Gelperin and Tank 1990; Gervais et al. 1996; Gelperin 1999). Inhibitors,research,lifescience,medical Work with the slug, Limax maximus, has shown that odor-cued associative conditioning alters the activity of procerebral neurons in a

spatially specific way (Kimura et al. 1998; Teyke et al. 2000). Given the small size of the nervous systems of snails and slugs: ~80,000–100,000 Inhibitors,research,lifescience,medical cells, approximately 75% of which are in the procerebra (Gelperin and Tank 1990; Balaban 2002), it is likely that the procerebrum plays a critical role in sensory processing in general, not just olfactory processing. Investigating a snail model in which a sensory modality other than olfaction is a significant determinant of behavior can shed light on the extent that the procerebrum is involved in Inhibitors,research,lifescience,medical processing of information in other sensory modalities. Snails, similar to other gastropods, secrete mucus from their foot which aids in locomotion, acting as both glue and a lubricant (Denny 1980a,b1980b). Inhibitors,research,lifescience,medical The mucus is left behind by the animal, forming a trail. Many species of gastropod have been reported to follow mucus trails of their own and other species to find mates, return to a “home” location, and in some cases to catch prey (for

review see (Wells and Buckley 1972; Ng et al. 2013). Euglandina rosea, the rosy wolfsnail, is a carnivorous land snail native to the Southeastern U.S. It tracks down its prey (other snails and slugs) as well as potential mates by following the mucus trails they leave behind. Euglandina snails follow STK38 mucus trails using a sophisticated chemosensory system that is separate from olfactory sensing (Chiu and Chou 1962). Previous work has shown that the sensory epithelia adapted for detecting mucus are on the long, mobile lip extensions that are absent in other snail species (Cook 1985a,b1985b; Clifford et al. 2003). While tracking prey, the Euglandina constantly touch their lip extensions to the trail being followed.