How much free will do you really have? Hypnosis is silly and there is no "Manchurian Candidate" scenario happening any time soon, but we're all inductance when you get right down to it. And that could be a future path in neuroscience.

A study Current Biology writes of a causal link between activity in the ventral tegmental area and choice behavior in primates; when electrical pulses are applied to the ventral tegmental area of their brain, macaques presented with two images change their preference from one image to the other. 

The ventral tegmental area is located in the midbrain and helps regulate learning and reinforcement in the brain's reward system. It produces dopamine, a neurotransmitter that plays an important role in positive feelings, such as receiving a reward. "In this way, this small area of the brain provides learning signals," explains Professor Wim Vanduffel of
KU Leuven. "If a reward is larger or smaller than expected, behavior is reinforced or discouraged accordingly."

And this effect can be artificially induced.

"In one experiment, we allowed macaques to choose multiple times between two images – a star or a ball, for example. This told us which of the two visual stimuli they tended to naturally prefer. In a second experiment, we stimulated the ventral tegmental area with mild electrical currents whenever they chose the initially nonpreferred image. This quickly changed their preference. We were also able to manipulate their altered preference back to the original favorite."

Could this method be used in the future to manipulate our choices? "Theoretically, yes. But the ventral tegmental area is very deep in the brain. At this point, stimulating it can only be done invasively, by surgically placing electrodes – just as is currently done for deep brain stimulation to treat Parkinson's or depression. Once non-invasive methods – light or ultrasound, for example – can be applied with a sufficiently high level of precision, they could potentially be used for correcting defects in the reward system, such as addiction and learning disabilities.

"Of course, there is also a potential danger here: the method could be used maliciously to manipulate a person's brain remotely without his knowledge. But as yet, there is no reason to worry. Non-invasive, high-precision methods for stimulating deep brain centers are not yet available."

Source: KU Leuven