Research subjects at the University of Minnesota fitted with a specialized noninvasive brain cap were able to move the robotic arm just by imagining moving their own arms. (Credit: University of Minnesota College of Science and Engineering)

A noninvasive technique, called electroencephalography (EEG) based brain-computer interface, has the potential to help millions of people who are paralyzed or have neurodegenerative diseases. The technique records weak electrical activity of the subjects’ brain through a specialized, high-tech EEG cap fitted with 64 electrodes and converts the thoughts into action by advanced signal processing and machine learning.

Wearing the EEG cap, subjects gradually learned to imagine moving their own arms without actually moving them to control a robotic arm in 3D space. They started from learning to control a virtual cursor on computer screen and then learned to control a robotic arm to reach and grasp objects in fixed locations on a table. Eventually, they were able to grasp objects in random locations on a table and move objects from the table to a three-layer shelf by only thinking about these movements.

The brain-computer interface technology works due to the geography of the motor cortex — the area of the cerebrum that governs movement. When humans move, or think about a movement, neurons in the motor cortex produce tiny electric currents. Thinking about a different movement activates a new assortment of neurons.