What would the Buddha have said? Monkeys have been trained to put themselves into a Zen-like trance – but out of desire for marshmallows rather than enlightenment.
The result suggests that simians could help to objectively test neurofeedback and other brain-training treatments for epilepsy or ADHD: they would be free of the placebo effects that humans might experience.
Neurofeedback involves teaching people to regulate their brainwaves and so control their state of mind by measuring the electrical activity of the brain and showing them that information. It is showing promise for reducing symptoms associated with epilepsy, ADHD and anxiety disorders, but it has been difficult to rule out the possibility that an enhanced awareness of the disease or a placebo effect is responsible, rather than the neurofeedback itself.
Animal research could help, because animals will not share our understanding of particular diseases and so will be immune to placebo or heightened-awareness effects, says Ingrid Philippens of the Biomedical Primate Research Centre in Rijswijk, the Netherlands. What is more, researchers can examine the physical structure of an animal’s brain to see if neurofeedback has a physical effect – a kind of investigation not possible with humans. “But first it is important to know if it’s possible to train monkeys on neurofeedback.”
To find out, Philippens and her colleague Raymond Vanwersch attached electrodes to the brains of marmoset monkeys to pick upelectroencephalogram (EEG) signals from the brain. Rather than showing the monkeys the EEG signal, as might be done in humans, Philippens and Vanwersch simply gave them a marshmallow reward every time they tuned their brain activity to a certain frequency range – in this case, 12 to 16 hertz.
In humans, this frequency is associated with a relaxed but focused state of mind. “It’s like meditation,” says Philippens. “When you see the monkeys doing it, they look very restful but they have focus, like they are staring at something,” she adds.
Two of the four monkeys tested learned to put themselves into this state within two training sessions; the others took four sessions to get the hang of it.
The monkeys may not realise that they are changing their brain activity, but it does show that they can consciously change their mood or state of mind, says Philippens. “This is an initial step for a much-needed scientific basis to neurofeedback.”
Journal reference: NeuroReport, DOI: 10.1097/wnr.0b013e3283360ba8