November 24, 2025

@michaelokun

What does your brain have to do w/ itching? Spoiler alert: The brain plays an important role in itch. Itch is a somatosensory signal that your brain interprets and shapes, linking sensation, emotion and action. Sun describes in a new paper in Nature Reviews Neuroscience how the brain and spinal cord coordinate the entire itch experience. Key points: - Itch signals begin in the skin, are sculpted in the spinal cord and then relayed to higher brain regions that determine what you feel emotionally and what you decide to do about it, including scratching. - Spinal circuits process chemical and mechanical itch using distinct excitatory and inhibitory neuron populations and these circuits gate how strongly itch signals rise up toward the brain. - Ascending pathways to the thalamus and parabrachial nucleus transmit itch information and engage broad brain networks that represent sensation, emotion and motivation. - Brain circuits linking the prefrontal cortex, insular cortex, amygdala and reward pathways determine both the negative and the positive affective components of itch, influencing whether folks scratch and how strongly they respond. My take: If you don't think the brain plays a role in itching, then think again. Here are 5 points that resonated w/ me: 1- Itch begins in the skin and is shaped in the spinal cord before you consciously feel it. Ultimately the brain acts as a final interpreter. 2- Chemical and mechanical itch follow different pathways, which helps explain why some itches sting, some tickle and some persist. 3- Brain regions that generate emotion play a major role, so itch frequently triggers discomfort, anxiety or an urge to escape the feeling. 4- Scratching is rewarding because brain reward circuits activate, which reinforces the itch scratch cycle and makes stopping difficult. 5- Chronic itch reflects plastic changes in spinal and brain circuits, meaning effective treatments will need to target both sensation and also address the brain’s emotional and motivational responses. https://www.nature.com/articles/s41583-025-00981-8 #michaelokun #fixelinstitute #neurology #neuroscience #itch