Researchers Identify Neural Circuit Linking Spinal Cord and Brain in Chronic Pain

Researchers have identified a specific neural circuit that links the spinal cord to the brain and back to the spinal cord, playing a role in the maintenance of chronic pain. The study, published in the journal Nature, focused on mouse models to deconstruct this pathway. The circuit involves projections from the spinal cord to the brain and returning signals that amplify pain signals over time.

The investigation mapped the spino-brain-spinal cord circuit using advanced imaging and genetic techniques. Sensory neurons in the spinal cord transmit initial pain signals to brain regions, including the parabrachial nucleus and insular cortex. From there, descending projections reinforce the pain response, leading to prolonged sensitivity.

dissect the circuit, the team employed optogenetics to activate or inhibit specific neurons.

Activation of the descending pathway in mice induced behaviors associated with ongoing pain, such as guarding and reduced activity. Inhibiting the circuit reduced pain hypersensitivity in models of inflammatory and neuropathic pain. The research highlighted the role of certain neuron types, including those expressing calcitonin gene-related peptide in the spinal cord.

These findings build on prior knowledge of ascending pain pathways but emphasize the bidirectional nature of the circuit in chronic conditions. The study was conducted by a team led by researchers at institutions including the University of Zurich and the Scripps Research Institute.

pain affects millions worldwide, often persisting after the initial injury heals.

This circuit's identification provides a anatomical basis for why pain becomes self-sustaining. Future research may explore pharmacological or neuromodulation approaches targeting this pathway. The study notes limitations, including its focus on rodent models, which may not fully translate to humans.