Figure 1.

Synaptic circuitry and experimental protocol. a, The N sensory neuron has a monosynaptic glutamatergic connection onto the L neuron (Yuan and Burrell, 2010). The T sensory neuron has both a monosynaptic electrical synapse and a polysynaptic glutamatergic connection onto the L neuron (Nicholls and Purves, 1970). The interneuron(s) mediating this polysynaptic component is unknown. b, Pretest recordings of the nociceptive N-to-L synapse were made before T-cell LFS (15 min; 1 Hz), and then posttest recordings were performed 0, 30, 60, or 120 min later, depending on the experiment. In some experiments, the LFS was replaced by a 15 min treatment of 2-AG or capsaicin.