Scientists have for the first time directed the decision making of monkeys using remote, ultrasonic brain stimulation.
For the study, published Wednesday in the journal Science Advances, researchers had a pair of macaque monkeys participate in a visual test designed to investigate basic decision making.
The monkeys were made to look at a target at the center of a screen before being presented with a second and third target to the left and right sides of the screen, one following the other.
Typically, macaques and other monkeys glance at the target that appears first, but researchers were able to alter the tendency by directing low-intensity ultrasound waves at the frontal eye fields of the two monkeys, the brain region that controls eye movement.
“Brief, low-intensity ultrasound pulses delivered non-invasively into specific brain regions of macaque monkeys influenced their decisions regarding which target to choose,” researchers wrote . “The effects were substantial, leading to around a 2:1 bias in choices compared to the default balanced proportion.”
Each of the ultrasonic pulses lasted 300 milliseconds and was applied just before the first secondary target appeared on the sides of the screen. The pulses cause brain tissue to vibrate and neurons to fire, altering the neuronal sequences in the targeted brain region.
When researchers directed ultrasonic waves on the monkey’s motor cortex, which doesn’t control the eye movements or decision making of monkeys, the visual choices of the two monkeys were unaffected.
Though a lot more testing of the technology and its potential is necessary, scientists estimate ultrasonic brain manipulation could eventually be used to study and treat decision-making disorders like addiction in humans.
“There are … tantalizing opportunities to apply ultrasonic neuromodulation to non-invasively modulate choice behavior in humans, with first applications aimed at determining the set of circuits involved in a given disorder in a given individual,” researchers wrote.