Friends and grandmothers

Abstract

How do neurons in the brain represent movie stars, famous buildings and other familiar objects? Rare recordings from single neurons in the human brain provide a fresh perspective on the question. It takes moments for the human brain to recognize a person or an object even if seen under very different conditions. This raises the question: can a single neuron respond selectively to a given face regardless of view, age, pose or context? That question — it has been called the search for the ‘grandmother neuron’ — is difficult to test. But now, in patients with intractable epilepsy who were implanted with depth electrodes for a clinical process, an answer has been obtained. Patients were asked to respond to images on computer screens, and the results showed that neurons are pretty single-minded in what they respond to. For instance, one neuron will respond selectively to different pictures of the actress Jennifer Aniston, one to basketball player Michael Jordan, and another to different views of the Tower of Pisa.