| First Author | Sun S | Year | 2017 |
| Journal | Neuron | Volume | 93 |
| Issue | 4 | Pages | 840-853.e5 |
| PubMed ID | 28231466 | Mgi Jnum | J:249930 |
| Mgi Id | MGI:6099190 | Doi | 10.1016/j.neuron.2017.01.012 |
| Citation | Sun S, et al. (2017) Leaky Gate Model: Intensity-Dependent Coding of Pain and Itch in the Spinal Cord. Neuron 93(4):840-853.e5 |
| abstractText | Coding of itch versus pain has been heatedly debated for decades. However, the current coding theories (labeled line, intensity, and selectivity theory) cannot accommodate all experimental observations. Here we identified a subset of spinal interneurons, labeled by gastrin-releasing peptide (Grp), that receive direct synaptic input from both pain and itch primary sensory neurons. When activated, these Grp(+) neurons generated rarely seen, simultaneous robust pain and itch responses that were intensity dependent. Accordingly, we propose a "leaky gate" model in which Grp(+) neurons transmit both itch and weak pain signals; however, upon strong painful stimuli, the recruitment of endogenous opioids works to close this gate, reducing overwhelming pain generated by parallel pathways. Consistent with our model, loss of these Grp(+) neurons increased pain responses while itch was decreased. Our new model serves as an example of non-monotonic coding in the spinal cord and better explains observations in human psychophysical studies. |
