Publications by authors named "Marcy Wainwright"
Article Synopsis
- * 14DFD reduces serotonin (5-HT) levels in the hemolymph, which contributes to the lack of memory sensitization and increased excitability of tail sensory neurons (TSNs) typically seen with normal feeding conditions.
- * Despite reduced 5-HT levels, applying 5-HT externally can still induce some sensitization and enhance TSN excitability in 14DFD Aplysia, although this effect is less pronounced compared to animals that underwent only short-term food deprivation (2DFD).
Article Synopsis
- - This study examines how Aplysia, a type of mollusk, balances defensive behaviors (like withdrawal) and feeding after experiencing aversive stimuli, showing significant changes for at least 24 hours.
- - The research found that increased excitability in tail sensory neurons enhances withdrawal reflexes, while decreased excitability in feeding neuron B51 suppresses feeding, both influenced by nitric oxide (NO).
- - A key discovery is that a signaling pathway involving protein kinase G (PKG) plays a crucial role in maintaining this behavioral balance, with NO activating PKG to mediate long-term changes in both sensitization and feeding suppression.
Article Synopsis
- The study investigates how aversive stimuli affect different behaviors—defensive (withdrawal) and appetitive (feeding)—in the mollusk Aplysia, finding that such stimuli enhance withdrawal reflexes while suppressing feeding.
- It highlights that serotonin (5-HT) is responsible for the sensitization (withdrawal enhancement), while nitric oxide (NO) is involved in the suppression of feeding, both in short-term and long-term scenarios.
- The research also uncovers a complex interaction between 5-HT and NO signaling, suggesting that multiple neurotransmitters play a role in modulating behavioral changes after exposure to aversive stimuli.
Article Synopsis
- Changes in neuron excitability significantly influence behavior, as demonstrated by the B51 neuron in the mollusk Aplysia, which is part of the feeding neural circuit.
- B51's excitability fluctuates based on external and internal factors, increasing during reward learning (via cAMP) and decreasing with aversive training protocols.
- The study found that cGMP can also reduce B51 excitability, mediated by nitric oxide activation of soluble guanylyl cyclase, highlighting a complex interplay between different cyclic-nucleotide pathways in regulating neuron behavior.
Article Synopsis
- - Following exposure to negative stimuli, organisms adjust their behavior by enhancing defensive actions while reducing non-defensive ones, requiring flexibility to adapt to changing internal or external conditions.
- - In the mollusk Aplysia, the behaviors of sensitization (increased defensive withdrawal) and feeding suppression are often seen together after training with aversive stimuli, but this study aimed to separate the two.
- - Manipulations like prolonged food deprivation and extended training with aversive stimuli showed that sensitization and feeding suppression can be uncoupled, indicating that these behaviors can change based on the organism's condition and experiences.
Article Synopsis
- - The study investigates how exposure to harmful stimuli leads to increased defensive responses, specifically the tail-induced siphon withdrawal reflex (TSWR), and reduced feeding behavior, focusing on the changes in neural excitability involved.
- - It found that increased excitability in tail sensory neurons (TSNs) correlates with heightened TSWR, while decreased excitability in a key feeding neuron (B51) corresponds with feeding suppression.
- - An in vitro model was created using specific ganglia to simulate these effects, revealing that both short-term and long-term changes in excitability were consistent with in vivo findings, and serotonin was effective in increasing TSN excitability without affecting B51.
Article Synopsis
- - Long-term sensitization (LTS) is linked to reduced feeding, which corresponds to a decrease in the excitability of the decision-making neuron B51.
- - Research focused on how Na and K channels affect B51's excitability showed that isolating Na channels during LTS training raised the firing threshold of B51 compared to untrained controls.
- - In contrast, isolating K channels did not display any notable differences in B51's activity between trained and untrained groups, indicating that Na channels play a key role in lowering B51 excitability during LTS.
Article Synopsis
- This study investigates how the marine mollusk Aplysia makes decisions about feeding after feeling full, focusing on a specific neuron called B51.
- Researchers found that after Aplysia was satiated, B51 showed decreased excitability for at least 24 hours, which correlated with the cessation of biting behavior in response to food.
- The findings suggest that B51's changes in activity play a key role in the decision-making process related to feeding after satiation, highlighting its importance in the neural mechanisms of decision-making at the single-cell level.
Article Synopsis
- - The study investigates how repeated aversive stimuli lead to long-term sensitization (LTS) in Aplysia, affecting defensive reflexes and suppression of feeding behaviors.
- - Researchers discovered that LTS training decreases the excitability of a key decision-making neuron (B51) in the feeding circuit, which recovers after 72 hours when LTS is no longer present.
- - The study concludes that while B51 plays a crucial role in feeding suppression, serotonin treatment to induce LTS does not impact feeding or B51's excitability, indicating serotonin is not involved in this process.
In Aplysia, noxious stimuli induce sensitization of defensive responses. However, it remains largely unknown whether such stimuli also alter nondefensive behaviors. In this study, we examined the effects of noxious stimuli on feeding.
View Article and Find Full Text PDFArticle Synopsis
- Repetitive stimulation of Aplysia can lead to long-term sensitization of their siphon-withdrawal reflex, affecting both the same side (ipsilateral) and the opposite side (contralateral) neurons.
- After 24 hours of long-term sensitization (LTS) training, brief shock treatments (BST) did not produce sensitization in animals previously trained only on the ipsilateral side or not trained at all.
- However, animals that underwent contralateral LTS training did exhibit increased sensitivity to the shock treatment, indicating that this training creates a latent memory that enhances future learning and response.
Article Synopsis
- - The process of neurite outgrowth is believed to play a role in long-term learning by helping create new synaptic connections.
- - In a study with Aplysia, the changes from long-term sensitization training were observed specifically on the trained side, affecting both behavior and the strength of synapses.
- - Despite training causing changes (like varicosity formation) on both sides of the animal, functional enhancements (connections with follower neurons) were only seen on the trained side, indicating that there are important regulatory steps involved after the initial growth process.
Present models of long-term sensitization in Aplysia californica indicate that the enhanced behavioral response is due, at least in part, to outgrowth of sensory neurons mediating defensive withdrawal reflexes. Presumably, this outgrowth strengthens pre-existing connections by formation of new synapses with follower neurons. However, the relationship between the number of sensorimotor contacts and the physiological strength of the connection has never been examined in intact ganglia.
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- This study focuses on how training protocols affect sensory neurons involved in the tail-siphon withdrawal reflex in Aplysia californica, looking specifically at their structure and memory retention in long-term sensitization.
- A 4-day training period led to significant growth in sensory neurons, while a 1-day training showed no morphological changes, even though both induced long-term behavioral sensitization.
- The findings suggest that longer training is crucial for physical changes in neurons, and that the timing of stimulation over several days plays a key role in the type of memory formed.