Neural circuits of Pain and Itch

Abstract

In this talk, I will describe an ex vivo somatosensory preparation that preserves the skin, peripheral nerves, and spinal cord in a continuous circuit. Using this system, we perform two-photon calcium imaging to monitor activity in both primary afferents and spinal neurons. A key advantage of this preparation is the ability to resolve defined neuronal populations: we can distinguish excitatory and inhibitory spinal neurons, identify spinal output neurons, and classify neurons based on their responses to specific neuromodulators. This approach enables a rare combination of experimental control and circuit-level resolution—allowing us to precisely manipulate sensory input, measure circuit output, and characterize the transformations that occur within identified spinal populations. Using this framework, I will show how this preparation has yielded new insights into the circuit mechanisms underlying itch and pain. Finally, I will propose a conceptual model for the fundamental organization of the neural circuits that give rise to these sensations.