2003). While the olfactory systems and olfactory learning abilities of several species of slugs and Gamma-secretase activity snails have been extensively studied (Chase 1981, 1985; Chase and Tolloczko 1993; Gelperin 1994; Gervais et al. 1996; Sahley and Crow 1998; Balaban 2002), almost nothing is known about the anatomy and physiology of mucus trail chemosensation. This study identifies connections between Inhibitors,research,lifescience,medical the lip extensions that mediate mucus trail detection and the cerebral ganglia, and demonstrates that mucus stimuli detected by the lip extensions

are processed in the same central ganglia and in the same manner as odor molecules detected by the olfactory system. Our anatomical and tract-tracing experiments show that in the Euglandina, the nerve from the inferior tentacle joins with the nerve from the lip extension, and the combined nerve connects to the procerebral Inhibitors,research,lifescience,medical lobe where neurons from the lip extension synapse in the cell body layer. While a large swelling at the point where the lip extension nerve and oral tentacle nerve comes together suggests a ganglion, it is Inhibitors,research,lifescience,medical unlikely that afferent nerves from the sensory epithelium terminate at this point as nickel-lysine and Lucifer yellow taken up by the distal ends of lip extension nerve are transported past this point to the cerebral ganglion. Our results

suggest that the connectivity and processing of input from the lip extension may have arisen in the Euglandina as an elaboration of the neural processing dedicated to the oral tentacle in other snails and slugs. This hypothesis is supported by our observation Inhibitors,research,lifescience,medical that in Euglandina, the lip extension nerve and oral tentacle nerve join, and the joined nerve Inhibitors,research,lifescience,medical enters the cerebral ganglion in the mid-lateral area where the oral tentacle enters in other land snails. In the Euglandina, backfilling

the lip extension nerve produces extensive labeling of the procerebrum appearing to cover the entire procerebrum, and resembles the results of backfilling of the Cantareus olfactory nerve more than the Cantareus oral tentacle nerve backfilling. Labeling of the Euglandina olfactory nerve produces labeling of the procerebrum that looks substantially the same as the labeling produced by backfilling the lip extension nerve. In addition to the similarity Liothyronine Sodium between the anatomical labeling, the neuronal activity of the Euglandina procerebrum is similar to neuronal activity recorded from the procerebra of other land snails. The activity is characterized by a widespread oscillation in local field potential with a frequency of 0.1–0.3 Hz, and stimulation with odorants changes the frequency and amplitude of the oscillations (Chase 1981; Gelperin and Tank 1990; Kimura et al. 1993; Delaney et al. 1994; Ermentrout et al. 1998).