Probing the coding logic of thermosensation using spinal cord calcium imaging

Area of Science:

• Neuroscience
• Sensory Physiology
• Spinal Cord Research

Background:

• The spinal cord dorsal horn is crucial for processing sensory information.
• High-throughput optical recording has advanced cortical studies but lagged in spinal cord research.
• Recent advancements enable in vivo two-photon spinal calcium imaging.

Purpose of the Study:

• To review the development of in vivo two-photon spinal calcium imaging.
• To characterize spinal cord responses to cutaneous thermal stimuli.
• To differentiate the neural coding of heat and cold and identify contributing peripheral inputs.

Main Methods:

• Development of an in vivo two-photon spinal calcium imaging preparation.
• Systematic characterization of spinal cord responses to thermal stimuli.
• Analysis of neuronal responses in the spinal dorsal horn.

Main Results:

• The study differentiated the spinal cord's coding of heat versus cold stimuli.
• TRPV1 channel knockout impaired warmth sensation.
• Somatostatin- and calbindin2-expressing neurons preferentially responded to heat.

Conclusions:

• In vivo two-photon spinal calcium imaging is a viable tool for studying spinal cord circuitry.
• Specific spinal neurons and pathways are involved in thermosensory coding.
• Future research will use this technology to explore chronic pain mechanisms.