Stanford researchers scanned teenagers listening to their mothers, having already shown that in young children her voice lights up half the brain. Something had switched. In children under about twelve, the reward circuitry fires harder for their mother's voice than for a stranger's. In adolescents it flips. The reward regions respond more strongly to unfamiliar voices, and her voice stops being the sound the system reaches for. The crossover happens somewhere between thirteen and fourteen. Nothing has gone wrong. The circuitry has not broken and she has not been demoted. It is being retuned deliberately, because a person who is going to leave home needs to start finding other people interesting, and the brain arranges that by making everyone outside the house more rewarding to listen to. Which means the thing every mother of a teenager describes has a mechanism. He is not ignoring her out of contempt. Her voice is no longer arriving at the part of him that used to light up for it. Two things worth holding onto here. The first is that the hearing and processing regions are still there and still working. He hears her perfectly. What changed is what his reward system does with the sound. The second is that this is temporary, and there is a whole literature on adult children and their mothers to say so. The circuitry is being repointed outward for the years he needs to build a life away from her. It is not being deleted. So a woman finds herself talking to somebody who used to run toward her voice across a car park, and who now barely registers it. That is her son's brain doing exactly what it is supposed to do, on schedule, and it is a horrible thing to be on the receiving end of. jneurosci.org/content/42/20/…