Many primates in Britain – one of Europe’s largest users – are used for curiosity driven “basic research” not required by law. This includes invasive neurology experiments, for which animals may have electrodes inserted directly into their brains to record brain cell activity as they perform tasks.

Classed as causing “moderate” suffering, a hole is cut into the monkeys’ skulls and a recording device implanted, in addition to a head restraint frame. Common adverse effects of this procedure include wound infections. Such single cell recordings can be, and are being, carried out in ethically controlled trials of patients undergoing brain surgery.