Final answer:
Short-term sensitization in Aplysia involves changes in synaptic strength, while long-term sensitization requires additional changes such as the production of new proteins and the growth of new synaptic connections.
Step-by-step explanation:
The synaptic basis for short-term sensitization in Aplysia is related to changes in synaptic strength. When the sea slug is exposed to a strong stimulus, the release of the neurotransmitter serotonin causes an increase in the number of synaptic connections. This leads to an enhanced response from the motor neurons, resulting in sensitization.
On the other hand, long-term sensitization involves additional changes at the synapse. A prolonged exposure to the strong stimulus triggers the activation of intracellular signaling pathways, leading to the production of new proteins and the growth of new synaptic connections. These changes help to maintain the sensitized state of the neurons over an extended period of time.