However, a team of researchers from Caltech and UCLA have discovered that a single neuron could be used to achieve some tasks, while a pair could allow binary operations to be performed.
Led by Dr Itzhak Fried, director of the Epilepsy Surgery Program at UCLA, the study looked at individual neurons associated with patients' favourite things.
Participants were asked to fire these neurons by thinking about those things - celebrities, TV shows and sports teams - and, in turn, control which of two images would appear on a screen ahead of them.
They quickly and easily learned control of the system, the researchers say, which could imply that sensors capable of reading a single neuron's state could allow control systems to be created with the ability to detect and respond to human thought in relatively simple terms.
