Meeting Abstract
The peripheral nervous system (PNS) of soft-bodied animals like molluscs is known to carry out complex sensory-motor computations, but little is known about the actual neural mechanisms. The notaspid sea-slug Pleurobranchaea californica relies heavily on chemotactile information from its anterior oral veil to locate and identify prey. We have previously found that 1) the PNS of the oral veil integrates input from multiple sites to send a somatotopic sensory map of sensory stimuli to the CNS for motor patterning of the turn response; and 2) Putatively dopaminergic sensory cells exist in the PNS with small axons afferent to the CNS; and 3) Dopamine and GABA have integral roles in peripheral sensory integration. Until now the PNS has not been easily accessible to electrophysiological analyses, in part because the afferent axons carrying appetitive and nociceptive sensory information to the CNS are likely too small to be recorded with conventional methods. However, recently we have found that local computations for chemical and tactile responses are accessible in simple suction electrode recordings of the chemotactile oral veil papillae. Whole-mount staining with phalloidin and anti-tubulin showed multiple clusters of putative ciliated sensory cells in papillae (dia. 15-25 µm) with associated muscle bands. The clusters could be recorded singly or multiply. Spontaneous activity of multiple units in a cluster was prominent, and was increased by appetitive chemical stimulation with trimethylglycine and shrimp blood, or by tactile stimuli. Some larger units appeared to be shared among clusters. The accessibilities of the papillae to electrophysiological, pharmacological, and morphological analyses appear to open investigation of the PNS to rapid progress.
