Robert Reinhart applies the electrical stimulus to subject Laura McClenahan. (John Russell/Vanderbilt University)
Robert Reinhart applies the electrical stimulus to subject Laura McClenahan. (John Russell/Vanderbilt University)

Teachers often urge their students to  put on their “thinking caps” as a way of encouraging serious thought. However, a real thinking cap could someday become a reality. New research shows it’s possible to control the ability to learn by applying mild electrical current to the brain.

Writing in the Journal of Neuroscience, the Vanderbilt University researchers say the results of their studies could eventually provide help to those wanting to improve their learning abilities and could also be used to treat various conditions such as schizophrenia and Attention Deficit Hyperactivity Disorder (ADHD).

The researchers made their findings after being intrigued by past studies that show a spike in negative voltage within the medial-frontal cortex of the brain milliseconds after a person makes an error. This area of the brain is thought to be responsible for the “oops” reaction whenever an error is made.

The previous research did not explain why this brain reaction occurs, so the Vanderbilt duo decided find out by testing several theories.  They also wanted see if that activity in the medial-frontal cortex would influence the ability to learn since the brain allows us to learn from our mistakes.

“And that’s what we set out to test: What is the actual function of these brainwaves?” said researcher Robert Reinhart, a Ph.D. candidate. “We wanted to reach into your brain and causally control your inner critic.”

The theories Reinhart and research partner Geoffrey Woodman, an assistant professor of psychology, wanted to test was to see if it was possible to control the brain’s electrophysiological – electrical properties of a living cell – response to mistakes, and if the effect could be purposely controlled either up or down depending on which direction an electrical current is applied to it. They also wanted to see how long the effect of the electrical application would last and whether the same methods could be used to control other tasks.

To conduct their tests, Reinhart and Woodman took an elastic cap with two electrodes fastened to saline-soaked sponges; the sponges were applied to the cheek and  crown of the head of the research subjects.

The researchers then applied 20 minutes of very mild transcranial – across or through the skull – direct current stimulation to each of their subjects.

During this process, the current traveled from one electrode, called the anodal electrode, which was attached to the crown of the head, through the skin, muscle, bones and brain, and out through the other electrode, or cathodal electrode, attached to the cheek in order to complete the circuit.

“It’s one of the safest ways to noninvasively stimulate the brain,” Reinhart said. “The current is so gentle that subjects reported only a few seconds of tingling or itching at the beginning of each stimulation session.”

The researchers conducted three of these transcranial stimulation sessions. Their subjects were randomly given either an anodal – current sent from the crown of the head to the cheek, cathodal – current sent from cheek electrode to crown – or a fake jolt that merely produced a tingling effect without actually affecting the brain.

After undergoing 20 minutes of trancranial stimulation, the test subjects were given a learning task that involved determining, through trial and error, which buttons on a game controller matched specific colors displayed on a monitor. The researchers would occasionally complicate the tests by showing the subjects a signal that told them not to respond. The subjects had less than a second to respond to each signal correctly, which made it easier for them to make mistakes, providing a number of opportunities for the medial-frontal cortex to fire.

The researchers measured the electrical brain activity of each subject as they made their way through the exercises. The measurements provided the researchers with a way to monitor how the brain changed at the very moment the subjects made an error and how the electrical stimulation influenced changes in brain activity.

Shortly after the researchers sent the current from the crown of the subject’s head to their cheek – an anodal current – they noticed that the spike in negative voltage was almost twice as large on average as without stimulation.

As a result of the anodal stimulation, the researchers found the subjects made fewer mistakes and that they actually learned from their errors faster than they did after a phony jolt was applied.

When they sent the current in the opposite direction, from the cheek to the crown of the head – cathodal current – the Vanderbilt duo saw the opposite of the anodal result take place.  They noticed that the spike in negative voltage was actually much smaller; the subjects wound up making many more errors and they took longer to learn each task.

The researchers noted that while the positive or negative effects generated by each of the stimulation patterns weren’t detected by the test subjects themselves, the results of each test displayed very clearly on their monitoring devices.

“This success rate is far better than that observed in studies of pharmaceuticals or other types of psychological therapy,” said Woodman.

The researchers said that their tests also revealed that the sessions of electrical stimulation did transfer to other tasks and the effects lasted for about five hours.




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