PHILIP O’KEEFE, a 62-year-old logistics worker and passionate fan of the Brisbane Lions, a local football team, also suffers from ALS, which has paralysed him. In 2020 a “stentrode” was inserted into a blood vessel in his brain from where it monitors activity in part of his cortex. The following year he used signals passed through that probe to send his first tweet: “hello, world! Short tweet. Monumental progress.” The Economist talked to him about the experience.

The Economist: What was your first reaction to the idea?