Patterns of electrical activity may present a predictive marker for impulsive behaviors, presenting deep brain stimulation (DBS) of the nucleus acumbens as a potential treatment to avert these, according to research from Stanford University (CA, USA).
Although an evolutionary necessity, impulse behaviors can become pathological, as exhibited in substance abuse, gambling, self-harm and outbursts of anger. “Imagine if you could predict and prevent a suicide attempt, a heroin injection, a burst of binge eating or alcohol intake, or a sudden bout of uncontrolled rage,” stated senior author, Casey Halpern (Stanford University).
DBS has been approved for use in treating Parkinson’s disease and essential tremor, and is currently being trailed for depression, obsessive compulsive disorder and other mental illnesses. In these cases, however, DBS fires on a pre-programed basis, whereas utilizing the novel signals uncovered in this research may provide targeted therapy, which could also reduce side effects of the treatment.
In the study, mice that were usually fed with standard food were given high-fat pellets for an hour a day over 10 days, and were allowed to eat as much as they wanted. Electrode arrays were implanted into their brains to monitor nucleus acumbens activity. Patterns of increased activity, restricted to a low frequency band known as delta, were observed immediately before eating, and did not emerge when mice fed on standard pellets.
The electrodes were then programed to deliver 10 second pulses, typical of DBS therapy, to the nucleus acumbens when increased delta activity was detected. This reduced over eating in the mice, without influencing social skills or other behaviors.
The team were also able to test their theory on a human patient, opting to receive DBS implantation as part of trials for obsessive compulsive disorder therapy. Electrical leads were connected to the patient’s nucleus acumbens and they were asked to perform a series of computerized tasks in exchange for monetary reward. Similarly to the over-indulgent mice, the patient became hyper-sensitized in anticipation of receiving a reward, as demonstrated by raised delta activity.
Researchers now hope their findings can be built upon to develop targeted, responsive neurostimulatory therapy to monitor and suppress the dangerous impulsive activities that characterize such a variety of mental illnesses.
Sources:Wua H, Millera KJ , Blumenfeldb. Closing the loop on impulsivity via nucleus accumbens delta-band activity in mice and man. Proc. Natl Acad. Sci USA. (2017) (Epub ahead of print);