Studies have shown increased risk taking in healthy individuals after low-frequency repetitive transcranial magnetic stimulation, known to transiently suppress cortical excitability, over the right dorsolateral prefrontal cortex (DLPFC). It appears, therefore, plausible that differential modulation of DLPFC activity, increasing the right while decreasing the left, might lead to decreased risk taking, which could hold clinical relevance as excessively risky decision making is observed in clinical populations leading to deleterious consequences. The goal of the present study was to investigate whether risk-taking behaviors could be decreased using concurrent anodal transcranial direct current stimulation (tDCS) of the right DLPFC, which allows upregulation of brain activity, with cathodal tDCS of the left DLPCF, which downregulates activity. Thirty-six healthy volunteers performed the risk task while they received either anodal over the right with cathodal over the left DLPFC, anodal over the left with cathodal over the right DLPFC, or sham stimulation. We hypothesized that right anodal/left cathodal would decrease risk-taking behavior compared with left anodal/right cathodal or sham stimulation. As predicted, during right anodal/left cathodal stimulation over the DLPFC, participants chose more often the safe prospect compared with the other groups. Moreover, these participants appeared to be insensitive to the reward associated with the prospects. These findings support the notion that the interhemispheric balance of activity across the DLPFCs is critical in decision-making behaviors. Most importantly, the observed suppression of risky behaviors suggests that populations with boundless risk-taking behaviors leading to negative real-life consequences, such as individuals with addiction, might benefit from such neuromodulation-based approaches.
Figure 1. Schematic representation of the experimental design. Each participant started to perform the risk task after receiving 5 min of stimulation. Stimulation continued throughout the task. The risk task was a decision-making task involving gambling. The task provided a measure of decision making under risk with little requirements on strategy and working memory.
Friday, November 23, 2007
Want to reduce risky behavior? Just pass a tiny current across your forehead.
Another brave new world item (from Fecteau et al.) - just what you need for your juvenile delinquent teenager! All you have to do is hook up a battery to two saline-soaked surface sponge electrodes to deliver anodal transcranial direct current stimulation (tDCS - two milliamps) to the right dorsolateral prefrontal cortex (DLPFC) to slightly up-regulate its activity, coupled with cathodal tDCS to the left DLPFC (current flows from anode to cathode). Here is the whole abstract and one figure: