Documentation: Interactive Habituation and Sensitization

Simulation video: https://youtu.be/A_kiGLG_wRg

GitHub link: https://github.com/thebraincellpie0630/Kandel-Simulation.git

Steps to install and run in your own device: https://docs.google.com/document/d/1nB5Z5uavWa2omgNkgwBotAg5iT8juTsbMZm5ZBvfT-k/edit?usp=sharing

Introduction

This project is an interactive simulation inspired by Eric Kandel’s Nobel Prize-winning research on the neural mechanisms underlying non-associative learning, particularly habituation and sensitization in Aplysia. This simulation visually represents the neural circuits involved, including sensory neurons, interneurons, motor neurons, and synapses, while incorporating graphical and interactive elements to dynamically demonstrate these processes. The goal is to provide an engaging and educational tool for students and researchers to explore these fundamental neuroscience concepts.

Background: Kandel’s Research on Aplysia

Eric Kandel’s studies on Aplysia provided crucial insights into the cellular and molecular basis of learning and memory. His research demonstrated that simple forms of learning, such as habituation and sensitization, are mediated by synaptic modifications rather than requiring new neurons. These findings laid the foundation for understanding plasticity in more complex nervous systems.

1. Habituation

• Habituation is a decrease in response to repeated, harmless stimuli.

• In Aplysia, repeated stimulation of the siphon leads to a progressive decline in the gill withdrawal reflex.

• Kandel’s work showed that this occurs due to synaptic depression at the sensory-to-motor neuron synapse, reducing neurotransmitter release.

2. Sensitization

• Sensitization is an increased response following a strong or noxious stimulus (e.g., tail shock).

• This process involves serotonin release from a facilitatory interneuron onto the synapse between the sensory and motor neurons.

• Serotonin enhances synaptic transmission by increasing neurotransmitter release, counteracting habituation.

Code Explanation

Graphical Representation of Neural Components

The simulation represents the core neural structures as follows:

• Sensory Neuron (Green Circle) – Activated when the siphon is stimulated, transmitting signals to the motor neuron and interneuron.

• Interneuron (Brown Circle) – Facilitates sensitization by releasing serotonin onto the sensory-motor synapse.

• Motor Neuron L7 (Orange Circle) – Receives input from the sensory neuron and interneuron, leading to gill withdrawal.

• Siphon (Blue Circle) – The external part of Aplysia where stimuli are applied, triggering sensory neuron activation.

Habituation Mechanism in the Code

• When the user clicks on the siphon, the sensory neuron activates the motor neuron, leading to gill withdrawal.

• If the stimulus is applied repeatedly within 5 seconds, withdrawal strength decreases, simulating synaptic depression.

• If no stimulus occurs within 5 seconds, the withdrawal resets to full strength, demonstrating recovery from habituation.

Sensitization Mechanism in the Code

• A “Sensitization” button applies a strong stimulus (analogous to tail shock).

• This triggers serotonin release from the interneuron onto the synapse between the sensory and motor neurons.

• The release of serotonin enhances synaptic transmission, increasing gill withdrawal strength despite prior habituation.

• Animated serotonin molecules visually travel from the interneuron to the synapse during this process.

Graphical Data Representation

• A real-time graph displays withdrawal strength over time.

• The graph updates dynamically based on user interactions, illustrating the effects of habituation and sensitization.

• The size of the graph has been adjusted for better readability and integration within the simulation.

User Interaction and Learning Outcomes

• Clicking the siphon reduces withdrawal strength if done within 5 seconds (habituation in action).

• If no stimulus is applied for 5 seconds, the withdrawal resets, demonstrating spontaneous recovery.

• Clicking the “Sensitization” button releases serotonin, increasing withdrawal strength and counteracting habituation.

• Visual animations dynamically update to show serotonin release, synaptic changes, and behavioral effects.

• Users can observe how repeated stimulation leads to plasticity at the synaptic level.

Conclusion

This interactive simulation effectively illustrates Kandel’s groundbreaking findings on habituation and sensitization, making these complex neuroscience principles accessible and engaging. By providing a hands-on experience, this tool enhances the understanding of non-associative learning and synaptic plasticity, key concepts in neurobiology.

Credit

All the simulation code was written with the help of Chat GPT (https://chatgpt.com/c/67a84677-7104-8013-b3ee-16a2adbe8a77)

Inspiration was original and there was no reference to any material online or from any person for the inspiration (even if it was there it is a coincidence).

The code documentation was also done with the help of ChatGPT. Experiment's introduction was written with the help of original journal papers.