Cell
Volume 168, Issues 1–2, 12 January 2017, Pages 295-310.e19
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Article
The Cellular and Synaptic Architecture of the Mechanosensory Dorsal Horn

https://doi.org/10.1016/j.cell.2016.12.010Get rights and content
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Highlights

  • Convergent LTMR and cortical inputs define the mechanosensory dorsal horn

  • A dorsal horn molecular-genetic toolbox defines 11 interneuron subtypes

  • Dorsal horn interneurons receive specific patterns of cortical and LTMR inputs

  • Dorsal horn interneurons modulate output pathways and tactile perception

Summary

The deep dorsal horn is a poorly characterized spinal cord region implicated in processing low-threshold mechanoreceptor (LTMR) information. We report an array of mouse genetic tools for defining neuronal components and functions of the dorsal horn LTMR-recipient zone (LTMR-RZ), a role for LTMR-RZ processing in tactile perception, and the basic logic of LTMR-RZ organization. We found an unexpectedly high degree of neuronal diversity in the LTMR-RZ: seven excitatory and four inhibitory subtypes of interneurons exhibiting unique morphological, physiological, and synaptic properties. Remarkably, LTMRs form synapses on between four and 11 LTMR-RZ interneuron subtypes, while each LTMR-RZ interneuron subtype samples inputs from at least one to three LTMR classes, as well as spinal cord interneurons and corticospinal neurons. Thus, the LTMR-RZ is a somatosensory processing region endowed with a neuronal complexity that rivals the retina and functions to pattern the activity of ascending touch pathways that underlie tactile perception.

Keywords

spinal cord interneurons
low-threshold mechanoreceptors
somatosensation
spinal cord dorsal horn
mouse molecular genetics
synaptic connectivity

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Co-first author

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Present address: Departments of Biochemistry and Molecular Biophysics and of Neuroscience, Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA

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