You know you want it. Just one more piece. That extra bit of pudding will be calling your name come Christmas Day, and you know it'll be hard to say no. Well, in potentially good news for the sweet-toothed, the burger enthusiasts and indulgers of all things naughty over nice, Stanford scientists have identified an electrical signature in the brain that precedes dangerous impulses, and delivering a timely pulse might be able to keep them in check.
"Impulses are normal and absolutely necessary for survival," says Casey Halpern, assistant professor of neurosurgery at Stanford University School of Medicine and senior author of the new study. "They convert our feelings about what's rewarding into concrete action to obtain food, sex, sleep and defenses against rivals or predators."
While impulses can be good, they can also be bad and bring consequences far worse than a ruined beach body. Impulses can drive gambling addiction, violence, drug-taking and especially heinous acts like putting on an episode of The Bachelor. Halpern and his team have uncovered what they describe as the smoking gun behind these irresistible urges, first in mice and then in humans.
The team switched the diets of laboratory mice from low-calorie pellets to a high-fat version, and allowed them to eat as much as they wanted during an hour-long period every day, for 10 days. The mice developed quite an appetite for the fatty pellets by the end of the 10 days and were pretty much eating them non-stop.
And their brains showed it. Throughout the experiment, electrodes were hooked up to the nucleus accumbens, a region of the brain that is critical for processing rewards. The team saw heightened activity in this reward center around one second before the mice chowed down on fatty pellets, while no uptick was observed before other rewarding activities like eating standard food and interactions with younger mice.
Building on this, the researchers adapted a form of deep-brain stimulation (DBS) used to treat things like Parkinson's, where electrical pulses are delivered to targeted brain regions. Where DBS devices currently in use deliver these pulses on a pre-programmed schedule, the Stanford team made use of a new generation of responsive devices that deliver tailored pulses when triggered by activity in the brain instead.
"There's no available responsive neuro-stimulation intervention for dangerous impulsive behavior yet, because until now no one's been able to document a characteristic signature in the brain that could be used for triggering pulse delivery by the device," says Halpern.
With this electrical signature in hand, Halpern and his team set up their experiments so that their electrodes delivered 10-second pulses to the nucleus accumbens whenever the heightened activity was detected. They found that these substantially reduced the fatty pellet binge-eating sessions, while having no impact on the rodent's general behavior.
They then tested out this approach on a person undergoing trials for obsessive-compulsive disorder, who had received a DBS device surgically hooked up to their nucleus accumbens as a result. The team was able to pin down the same electrical signal in the patient's brain as they carried out a cash-reward experiment, and although more investigations are required before these behavior-altering jolts are delivered to a human subject, the team is optimistic about the way things are headed.
If that leap can be made, it does raise the prospect of using this type of therapy to treat a wide range of behaviors that can be detrimental to one's health or the health of others. Imagine if once you'd consumed your daily intake of sugar, you simply never felt the urge to eat more cake. Or the Harvey Weinsteins of the world could keep their hands to themselves. Or serial gamblers would know when to call it a day.
"The fact that we saw a similar signal prior to two different behaviors, both intended to obtain rewards – food in the case of mice, money in the case of the human subject – to which the individuals had become hyper-sensitized by their repeated exposure suggests that this signal may be common to many impulsive behaviors, making them amenable to treatment along similar lines," says Halpern.
The research was published in the Proceedings of the National Academies of Sciences.
Source: Stanford University
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