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J Exp Biol

Title:		Sensory input from the osphradium modulates the response to memory-enhancing stressors in Lymnaea stagnalis
Author(s):		Karnik V; Braun M; Dalesman S; Lukowiak K;
Address:		"Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, T2N 4N1"
Journal Title:		J Exp Biol
Year:		2012
Volume:		215
Issue:		Pt 3
Page Number:		536 - 542
DOI:		10.1242/jeb.061432
ISSN/ISBN:		1477-9145 (Electronic) 0022-0949 (Linking)
Abstract:		"In the freshwater environment species often rely on chemosensory information to modulate behavior. The pond snail, Lymnaea stagnalis, is a model species used to characterize the causal mechanisms of long-term memory (LTM) formation. Chemical stressors including crayfish kairomones and KCl enhance LTM formation (>/=24 h) in Lymnaea; however, how these stressors are sensed and the mechanism by which they affect the electrophysiological properties of neurons necessary for memory formation are poorly understood. Here, we assessed whether the osphradium, a primary chemosensory organ in Lymnaea, modulates LTM enhancement. To test this we severed the osphradial nerve proximal to the osphradium, using sham-operated animals as controls, and assessed the behavioral and electrophysiological response to crayfish kairomones and KCl. We operantly conditioned aerial respiratory behavior in intact, sham and osphradially cut animals, and tested for enhanced memory formation after exposure to the chemical stressors. Sham-operated animals displayed the same memory enhancement as intact animals but snails with a severed osphradial nerve did not show LTM enhancement. Extracellular recordings made from the osphradial nerve demonstrate that these stressors evoked afferent sensory activity. Intracellular recordings from right pedal dorsal 1 (RPeD1), a neuron necessary for LTM formation, demonstrate that its electrophysiological activity is altered by input from the osphradium following exposure to crayfish kairomones or KCl in sham and intact animals but no response is seen in RPeD1 in osphradially cut animals. Therefore, sensory input from the osphradium is necessary for LTM enhancement following exposure to these chemical stressors"
Keywords:		"Animals Chemoreceptor Cells/*physiology Conditioning, Operant/physiology Electrophysiological Phenomena/physiology Lymnaea/*physiology Memory, Long-Term/*physiology Neurons/physiology Sensation Sensory Receptor Cells/*physiology Stress, Psychological;"
Notes:		"MedlineKarnik, Vikram Braun, Marvin Dalesman, Sarah Lukowiak, Ken eng Canadian Institutes of Health Research/Canada Research Support, Non-U.S. Gov't England 2012/01/17 J Exp Biol. 2012 Feb 1; 215(Pt 3):536-42. doi: 10.1242/jeb.061432"