Humans and monkeys can learn to fire neurons in particular regions of the brain at will using a feedback mechanism. They can, for example, control the movement of motor neurons even without making any physical movements. But what effect does that firing have on the cognition or behavior of the monkey (or person)?
Robert Schafer and Tirin Moore of the Stanford University School of Medicine, studied that question using neurons at 94 sites in the frontal eye field (FEF), an area of the brain involved in eye movement, in two monkeys. The answer they got was something that might be a lesson for those with attention deficit disorders: controlling those neurons improves visual attention.
“Our main question was simply, if a human or animal could voluntarily control FEF neurons, without being instructed to do anything else, what would the consequences be for the subject? In other words, what cognitive or motor effects might they experience while controlling the neurons?” says Moore.
The team started by getting the monkeys to control the FEF activity, by giving them a reward either for increasing or decreasing the firing of the neurons. With the monkeys primed and able to control the neuronal activity, the scientists led them through a series of cognitive tests to see what effect regulating the neurons might have.
For example, they tested the monkeys’ ability to direct a saccade at a search target on a screen. But there was no difference in their performance whether they were increasing or decreasing the neuronal firing rate. There did not seem to be a motor effect from the FEF control. But when the task was to distinguish targets from distracters within the field of view that corresponded to the FEF neurons—a sign of their ability to focus—the increased firing rate made the monkeys significantly better. The results, which indicate that voluntary control of neuronal activity can improve attention, were published yesterday in Science.
Moore says the results might provide some broad understanding of how neurofeedback, like that used to train the monkeys to control neuronal activity, might be an effective treatment for ADHD.
Neurofeedback is already sometimes used to treat epilepsy, neuropsychiatric disorders, and attention deficit disorders. But Sandra Loo, a pediatric neuropsychologist at UCLA, is skeptical. She says most studies of neurofeedback have been uncontrolled and that the most recent controlled study showed no significant benefits. “More research is needed to determine the practical benefit of these findings and the clinical efficacy of neurofeedback for ADHD,” she says.
Hartmut Heinrich of the Departemnt of Child and Adolescent Mental Health at the University of Erlangen admits “there is still a great lack of knowledge regarding how neurofeedback training actually works” but he says his studies on ADHD demonstrated clinical efficacy, and show an association between clinical or behavioral improvements and neurophysiological effects.
Heinrich says the new findings offer a helpful hint for neurofeedback by showing that voluntary control over a particular brain pattern has to be applied in the right context. “Situations have to be identified and practiced in which the learned strategies can be useful for a child. Otherwise, sufficient clinical improvements cannot be expected.”
Moore says the technique opens the door to other similar studies: “One obvious extension is simply to repeat the same experiment in other parts of the brain, asking how voluntary control in various areas affects cognitive functions, neurophysiology and behavior.”