Single-cell analysis of peptide expression and electrophysiology of right parietal neurons involved in male copulation behavior of a simultaneous hermaphrodite

Male copulation is a complex behavior that requires coordinated communication between the nervous system and the peripheral reproductive organs involved in mating. In hermaphroditic animals, such as the freshwater snail Lymnaea stagnalis, this complexity increases since the animal can behave both as male and female. The performance of the sexual role as a male is coordinated via a neuronal communication regulated by many peptidergic neurons, clustered in the cerebral and pedal ganglia and dispersed in the pleural and parietal ganglia. By combining single-cell matrix-assisted laser mass spectrometry with retrograde staining and electrophysiology, we analyzed neuropeptide expression of single neurons of the right parietal ganglion and their axonal projections into the penial nerve. Based on the neuropeptide profile of these neurons, we were able to reconstruct a chemical map of the right parietal ganglion revealing a striking correlation with the earlier electrophysiological and neuroanatomical studies. Neurons can be divided into two main groups: (i) neurons that express heptapeptides and (ii) neurons that do not. The neuronal projection of the different neurons into the penial nerve reveals a pattern where (spontaneous) activity is related to branching pattern. This heterogeneity in both neurochemical anatomy and branching pattern of the parietal neurons reflects the complexity of the peptidergic neurotransmission involved in the regulation of male mating behavior in this simultaneous hermaphrodite

Neural Representation of Motor Output, Context and Behavioral Adaptation in Rat Medial Prefrontal Cortex During Learned Behavior

Selecting behavioral outputs in a dynamic environment is the outcome of integrating multiple information streams and weighing possible action outcomes with their value. Integration depends on the medial prefrontal cortex (mPFC), but how mPFC neurons encode information necessary for appropriate behavioral adaptation is poorly understood. To identify spiking patterns of mPFC during learned behavior, we extracellularly recorded neuronal action potential firing in the mPFC of rats performing a whisker-based “Go”/“No-go” object localization task. First, we identify three functional groups of neurons, which show different degrees of spiking modulation during task performance. One group increased spiking activity during correct “Go” behavior (positively modulated), the second group decreased spiking (negatively modulated) and one group did not change spiking. Second, the relative change in spiking was context-dependent and largest when motor output had contextual value. Third, the negatively modulated population spiked more when rats updated behavior following an error compared to trials without integration of error information. Finally, insufficient spiking in the positively modulated population predicted erroneous behavior under dynamic “No-go” conditions. Thus, mPFC neuronal populations with opposite spike modulation characteristics differentially encode context and behavioral updating and enable flexible integration of error corrections in future actions

THE EFFECT OF LIGHT ON INDUCED EGG LAYING IN THE SIMULTANEOUS HERMAPHRODITE LYMNAEA STAGNALIS

ABSTRACT Reproduction is influenced by many external factors. For egg laying of pond snails, one important trigger is the transfer from dirty, oxygen-poor water to clean, oxygen-rich water. This response is due to the combined effects of elevated oxygen level, chemical water composition and clean substrate. Whether this clean-water stimulus (CWS) resembles the natural egg-laying process has remained untested. Given that the response relies heavily on a pretreatment that suppresses egg laying, the animal's internal state is clearly important. Egg laying is known to be influenced by day length, hence external factors signifying time of day or season may be involved. We here study the effect of light on the CWS in the freshwater pulmonate Lymnaea stagnalis. Clean water was more effective in inducing oviposition in the light than during darkness, irrespective of the presence of eyes. Thus, light has a profound influence on egg laying, which is most likely mediated by nonocular photoreceptors. We show that more eggs are laid during the day than during the night in wild-caught animals kept outside, which indicates that the effect of light on CWS-induced egg laying is relevant for the induction of egg laying under natural conditions

Modulatory role for the serotonergic cerebral giant cells in the feeding system of the snail, Lymnaea. I. Fine wire recording in the intact animal and pharmacology

1. The role of the paired serotonergic cerebral giant cells (CGCs) in the feeding system of Lymnaea was examined by electrophysiological and pharmacological techniques. 2. The firing characteristics of the CGCs were recorded by fine wires attached to their cell bodies in freely moving intact snails (in vivo recording) and their "physiological" rates of firing determined during feeding and other behaviors. 3. The mean CGC firing rates recorded in vivo varied between 1 and 20 spikes/min but never reached the average rates seen in the isolated CNS (60-120 spikes/min). Maximum rates of firing were seen during bouts of radula biting/rasping movements characteristic of the consummatory phase of feeding (15 +/- 1.69 spikes/min, mean +/- SE, range 7-20 spikes/min), with lower rates seen during locomotion (6.7 +/- 0.75 spikes/min; range 5-9 spikes/min. The cells were rarely active when the animal was quiescent (1.45 +/- 0.91 spikes/min; range 0-2 spikes/min). 4. In vivo recorded CGC firing was phase locked to the feeding movements of the animal, with spikes occurring just before the opening of the mouth, during the protraction phase of the feeding cycle. 5. Evoking firing rates on the CGCs in the isolated preparation similar to those seen in vivo during rasping movements (7-20 spikes/min) did not elicit a fictive feeding pattern in an inactive preparation. Neither did bath application of 10(-9) M serotonin (5-HT; the transmitter of the CGCs). 6. To allow the modulatory role of the CGCs to be examined during patterned activity, the fictive feeding pattern was evoked in the isolated preparation by injecting depolarizing current into a modulatory neuron, the slow oscillator (SO). 7. The tonic firing activity of the CGCs was accurately maintained by current injection in the isolated preparation at rates equivalent to that occurring during feeding, locomotion, and quiescence in the intact snail. This was possible where the CGCs became silent after 1-2 h. Only when the CGCs activity was maintained at a rate (approximately 15 spikes/min) similar to that occurring during rasping, was the SO able to drive a full, high-frequency fictive feeding pattern (15-20 cycles/min). At lower rates of CGC firing, the SO-driven rhythm was either of lower frequency or no rhythm occurred at all (CGCs silent). 8. In many isolated preparations (80%) the CGCs remained active, and it was difficult to maintain specific levels of tonic activity by current injection.(ABSTRACT TRUNCATED AT 400 WORDS) </jats:p

The neuropeptide schistosomin and haemolymph from parasitized snails induce similar changes in excitability in neuroendocrine cells controlling reproduction and growth in a freshwater snail

Infection of the snail Lymnaea stagnalis with the schistosome parasite Trichobilharzia ocellata results in inhibition of reproduction and in giant growth. Parasite-related effects on the neuroendocrine centres that control these processes were studied electrophysiologically. Haemolymph from infected snails reduced the excitability of the caudodorsal cells, which control egg laying. In contrast, the excitability of the growth-controlling Light Green Cells was increased under these conditions. The endogenous anti-gonadotropic neuropeptide schistosomin, the presence of which is strongly enhanced in parasitized snails, induced similar effects. Schistosomin apparently plays an important role in the balance between reproduction and growth in Lymnaea. This balance is severely disturbed during parasitic infection, probably as a result of the release of the peptid

High-frequency burst spiking in layer 5 thick-tufted pyramids of rat primary somatosensory cortex encodes exploratory touch

In order to investigate the information encoded by spiking activity in different neuronal cell types in the primary somatosensory cortex, de Kock et al performed electrophysiological recordings in untrained rats. They demonstrated that an increase in high-frequency burst spiking in thick tufted pyramids in layer 5 of the cortex allow accurate encoding of exploratory whisker touch