Question

Which of the following statements about sensitization of the gill withdrawal reflex in Aplysia are true?

1) Serotonin release onto sensory neurons activates NMDA receptors.
2) Sensitization is caused by an increased release of serotonin onto the presynaptic terminal of sensory neurons in the reflex pathway for gill withdrawal.
3) Sensitization results in increased glutamate release from the sensory neuron onto the motor neuron.
4) Sensitization can last for hours up to days.
5) Sensitization results in a decrease in gill withdrawal after multiple touches to the siphon.

Answer 1

Sensitization of the gill withdrawal reflex in Aplysia involves an increased release of serotonin and glutamate, leading to a stronger and more persistent gill withdrawal response, lasting from hours to days.

Step-by-step explanation:

Understanding the sensitization of the gill withdrawal reflex in Aplysia, several key points must be considered:

• Serotonin release onto sensory neurons does not activate NMDA receptors but rather contributes to the sensitization process by enhancing neurotransmitter release.
• Sensitization involves increased release of serotonin onto the presynaptic terminal of sensory neurons, which then leads to an enhanced response in the reflex pathway for gill withdrawal.
• Consequently, sensitization results in increased release of glutamate from the sensory neuron onto the motor neuron, facilitating a stronger withdrawal reflex.
• Sensitization can last for hours to days, showcasing the persistence of this form of learning.
• Contrary to causing a decrease, sensitization actually results in an increase in gill withdrawal response after repeated touch stimuli to the siphon, signifying an enhanced defensive reaction.