A fundamental question in neuroscience is how we perceive and respond to our environment. Our laboratory uses mouse molecular genetics, circuit mapping, and electrophysiological analyses to gain understanding of the development, organization, and function of neural circuits that underlie the sense of touch. Mouse molecular genetic approaches are used to identify, visualize, and functionally manipulate each of the physiologically defined classes of low-threshold mechanosensory neurons (LTMRs), the primary cutaneous sensory neurons that mediate the sense of touch. We have also gained genetic access to neurons that receive and process LTMR inputs in the spinal cord and propagate this information to the brain. Our current goals are to discover: 1) unique functions and properties of LTMR subtypes; 2) the organization and logic of synaptic connections between LTMR subtypes, spinal cord dorsal horn interneurons and projection neurons, and dorsal column nuclei neurons; 3) ascending pathways that underlie the perception of touch, 4) cellular and circuit level alterations that underlie touch sensitivity deficits in autism spectrum disorders and neuropathic pain, and; 5) mechanisms by which primary somatosensory neurons and touch circuit organization are established during development.