Comparative study of visuo-vestibular conditioning in Lymnaea stagnalis.
In this review, we compare the current understanding of visuo-vestibular conditioning in Hermissenda crassicornis and Lymnaea stagnalis on the basis of behavioral, electrophysiologic, and morphologic studies. Paired presentation of a photic conditioned stimulus (CS) and an orbital rotation unconditioned stimulus (US) results in conditioned escape behavior in both species. In Hermissenda, changes in excitability of type B photoreceptors and morphologic modifications at the axon terminals follow conditioning. Caudal hair cells, which detect mechanical turbulence, have reciprocal inhibition with type B photoreceptors. In Lymnaea, the interaction between photoreceptors and hair cells is dependent on statocyst location. Furthermore, the organization of the Lymnaea eye is complex, with more than 100 photoreceptors distributed in a uniquely folded retina. Although the optimal conditions to produce long-term memory (memory persistent for >1 week) are almost identical in Hermissenda and Lymnaea, physiologic and morphologic differences suggest that the neuronal mechanisms underlying learning and memory are distinct.
Sakakibara
Manabu
M
Laboratory of Neurobiological Engineering, Department of Biological Science and Technology, School of High-Technology for Human Welfare, Tokai University, Nishino 317, Numazu 410-0321, Shizuoka, Japan. manabu@tokai.ac.jp
D000818:Animals; D003214:Conditioning, Classical / Q000502:physiology*; D004924:Escape Reaction / Q000502:physiology; D018069:Hair Cells, Vestibular / Q000033:anatomy & histology / Q000502:physiology*; D049870:Hermissenda / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology; D008195:Lymnaea / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology*; D008568:Memory / Q000502:physiology; D008959:Models, Neurological; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000502:physiology*; D010812:Physical Stimulation; D014785:Vision, Ocular / Q000502:physiology