Researchers used advanced techniques to detect if patients in a coma or vegetative state were following instructions.

A quarter of patients left unresponsive after a severe brain injury can still perform cognitive tasks, a study suggests.

The syndrome known as cognitive motor dissociation (CMD) can happen when a person in a coma or vegetative state appears unresponsive, but still shows brain activity related to intentional thinking.

To detect if patients were following instructions, researchers analysed brain imaging scans called functional magnetic resonance imaging (fMRI), as well as a test that records the electrical activity in the brain, known as electroencephalography (EEG).