Changes in the Activity of a CPG Neuron After the Reinforcement of an Operantly Conditioned Behavior inLymnaea

Abstract

We have previously shown that the aerial respiratory behavior of the mollusk Lymnaea stagnalis can be operantly conditioned, and the central pattern generating (CPG) neurons underlying this behavior have been identified. As neural correlates of operant conditioning remain poorly defined in both vertebrates and invertebrates, we have used the Lymnaea respiratory CPG to investigate neuronal changes associated with the change in behavior after conditioning. After operant conditioning of the intact animals, semi-intact preparations were dissected, so that changes in the respiratory behavior (pneumostome openings) and underlying activity of the identified CPG neuron, right pedal dorsal 1 (RPeD1), could be monitored simultaneously. RPeD1 was studied because it initiates the rhythmic activity of the CPG and receives chemo-sensory input from the pneumostome area. Pneumostome openings and RPeD1 activity were monitored both before and after a reinforcing training stimulus applied to the open pneumostome of operantly conditioned and yoked control preparations. After presentation of the reinforcing stimulus, there was a significant reduction in both breathing behavior and RPeD1 activity in operant preparations but not in yoked and naïve controls. Furthermore these changes were only significant in the subgroup of operantly conditioned animals described as good learners and not in poor learners. These data strongly suggest that changes in RPeD1 activity may underlie the behavioral changes associated with the reinforcement of operant conditioning of the respiratory behavior.

A flavanoid component of chocolate quickly reverses an imposed memory deficit

“…In addition, we have demonstrated that: (1) memory recall is context specific (Haney and Lukowiak, 2001); (2) one-trial learning occurs (Martens et al, 2007); (3) reconsolidation and extinction occur (Sangha et al, 2003a,b); (4) forgetting is an active process ; and (5) a false memory can be implanted into the snail following activation of the memory . We have also shown that: (1) a single neuron, RPeD1 is a necessary site for LTM formation (Scheibenstock et al, 2002) and significant changes in synaptic input as well as changes in neuronal excitability of this neuron have been correlated with LTM (Spencer et al, 1999(Spencer et al, , 2002Braun and Lukowiak, 2011); (2) learning and memory formation can be demonstrated in an in vitro semi-intact preparation (McComb et al, 2005); (3) differences in cognitive ability occur at both the behavioural (Orr et al, 2009;Dalesman et al, 2011a,b,c) and neuronal levels Braun et al, 2012); and (4) a partial proteomics profile exists for changes underlying LTM formation . Finally, a number of environmentally relevant stressors either enhance or block memory 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.…”

Operant conditioning in invertebrates

“…The accounts of the underlying neurobiology include the differential requirements of local translation and transcription for intermediate-and long-term memory, respectively, as well as neural correlates in neurons in the CPG [46 ,49 ,55,56 ]. Importantly, the CPG activity initiating neuron RPeD1 (right pedal dorsal 1; see Figure 3d) shows a lower spontaneous firing frequency in semi-intact preparations from trained animals after a brief reminder training [56 ]. In isolated ganglia of operantly trained animals, RPeD1 is quiescent more often than in preparations from yoked control animals, and the efficacy of the excitatory connection from RPeD1 to IP3 (input 3 interneuron; see Figure 3d) is reduced [55].…”