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A non-canonical retina-ipRGCs-SCN-PVT visual pathway for mediating contagious itch behavior
Fang Gao1, Jun Ma1, Yao-Qing Yu2
1Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA; Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Cell Reports
|October 5, 2022
Summary
Social animals use contagious itch to signal danger. A new visual pathway from the retina to the SCN and PVT, involving intrinsically photosensitive retinal ganglion cells (ipRGCs), mediates this behavior, independent of the visual cortex.
Area of Science:
- Neuroscience
- Animal Behavior
- Sensory Systems
Background:
- Contagious itch is vital for social animals, signaling environmental threats.
- Gastrin-releasing peptide (GRP) and its receptor (GRPR) in the suprachiasmatic nucleus (SCN) are known to mediate this behavior in mice.
Purpose of the Study:
- To elucidate the neural pathways involved in transmitting visual information related to contagious itch.
- To identify the specific neuronal populations and signaling mechanisms underlying this social behavior.
Main Methods:
- In vivo calcium imaging and extracellular recordings were used to monitor neural activity.
- Investigated the role of intrinsically photosensitive retinal ganglion cells (ipRGCs) and PACAP-PAC1R signaling.
- Examined the involvement of the SCN, PVT, visual cortex, and superior colliculus.
Main Results:
- ipRGCs transmit visual itch information from the retina to GRP neurons in the SCN via PACAP-PAC1R signaling, independent of melanopsin.
- GRPR neurons in the SCN relay itch signals to the paraventricular nucleus of the thalamus (PVT).
- The visual cortex and superior colliculus are not involved in processing contagious itch information.
Conclusions:
- A novel visual pathway (retina-ipRGC-SCN-PVT) mediates contagious itch behavior.
- This pathway likely evolved for motion vision, encoding environmental cues for anticipatory behavioral imitation.
- Understanding this pathway offers insights into social signaling and threat detection in animals.
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