Pain-related neuronal ensembles in the primary somatosensory cortex contribute to hyperalgesia and anxiety

The mechanism by which acute pain or itch information at the periphery is pro-cessed in the primary somatosensory cortex (S1) remains unclear. To elucidate this, we used a viral-mediated targeted-recombination-in-active population sys-tem to target S1 neuronal ensembles that are active during pain or itch sensa-tions. We induced the expression of excitatory or inhibitory designer receptors exclusively activated by designer drugs in pain-or itch-related S1 neurons. We identified neuronal populations in mice that regulate the sensory components of pain and itch in the S1 hind paw region. Notably, the neuronal circuit between pain-related S1 neurons and the parafascicular nucleus contributed to hyperalge-sia and anxiety-like behavior. We propose that S1 plays an essential role in sensory and affective responses to noxious stimuli, such as pain.