The idealized diagram I (obviously) drew, depticting short-term sensitization of gill withdrawal in Aplysia
As the name implies, this is the mechanism underlying organism-wide increased sensitivity to touch after it has been shocked at just one site.
Short-term sensitization of gill withdrawal in aplysia occurs when the organism’s tail is subjected to a stimulus shock, thereby activating tail sensory neurons, and by extension, the modulatory interneurons which innervate with presynaptic terminals of the gill sensory neurons. At any one of these synaptic clefts, serotonin is released by the interneuron and received by G-coupled serotonin receptors, which, in the presence of ATP, catalitically releases cAMP, activating protein kinase A (PKA). PKA then mediates phosporylation of the K+ channels, which reduces the probability that it will open, enhancing Ca2+ entry through its respective ionic channel and facilitating a greater release of glutamate into the synaptic cleft between the siphon sensory neuron and the gill motor neuron.