The Soma of RPeD1 Must Be Present for Long-Term Memory Formation of Associative Learning inLymnaea

Abstract

The cellular basis of long-term memory (LTM) storage is not completely known. We have developed a preparation where we are able to specify that a single identified neuron, Right Pedal Dorsal 1 (RPeD1), is a site of LTM formation of associative learning in the pond snail, Lymnaea stagnalis. We demonstrated this by ablating the soma of the neuron but leaving behind its functional primary neurite, as evidenced by electrophysiological and behavioral analyses. The soma-less RPeD1 neurite continues to be a necessary participant in the mediation of aerial respiratory behavior, associative learning, and intermediate-term memory (ITM); however, LTM cannot be formed. However, if RPeD1's soma is ablated after LTM consolidation has occurred, LTM can still be accessed. Thus the soma of RPeD1 is a site of LTM formation.

Operant Conditioning of Gill Withdrawal inAplysia

“…EXT or Ext, Extinction; PRE, pretest period; Con, control; Exp, experimental. involve changes in the biophysical properties or synaptic connections of the L25 and R25 neurons, which are the major elements of the pattern generator for the contractions (Byrne and Koester, 1978;Byrne, 1983;Koester, 1989), and changes in the frequency of spontaneous contractions could involve changes in the firing or effects of the peptidergic modulatory neurons R15 and R20 (Alevizos et al, 1989(Alevizos et al, , 1991, which produce slow excitation of the L25 and R25 neurons. Such changes in the properties of neurons in a central pattern generator are thought to contribute to operant conditioning of feeding in Aplysia (Nargeot et al, 1999a,b;Brembs et al, 2002) and may also contribute to operant conditioning of aerial respiration in Lymnea (Spencer et al, 1999(Spencer et al, , 2002Scheibenstock et al, 2002). Because the gill often appears to contract just before it reaches the criterion level during training (Fig.…”

Cognition in Invertebrates

“…Aversive operant conditioning of Lymnaea's aerial respiratory behavior involves stimulating the animal's pneumostome when it surfaces and attempts to breathe (Lukowiak et al, 1996(Lukowiak et al, , 1998(Lukowiak et al, , 2000Lukowiak and Syed, 1999;Spencer et al, 1999;Haney and Lukowiak, 2001;McComb et al, 2002McComb et al, , 2003Sangha et al, 2002Sangha et al, , 2003Scheibenstock et al, 2002;Spencer et al, 2002). The stimulation is aversive, which leads to the animal closing the pneumostome and learning as training progresses to reduce its attempts to open the pneumostome.…”

Heat stress enhances LTM formation inLymnaea: role of HSPs and DNA methylation

“…This is because the sufficiency and necessity of the neuronal circuit has been experimentally shown (Syed et al, 1990(Syed et al, , 1992Scheibenstock et al, 2002). Lymnaea satisfy their respiratory requirements using both cutaneous and aerial respiration (Lukowiak et al, 1996).…”