In a recent paper in Frontiers in Decision Neuroscience, Sela and colleagues 2012 used tACS to investigate the effects of oscillatory prefrontal theta stimulation, a frequency involved in regulatory control during decision-making processes Sela et al., 2012. Subjects performed a modified version of the Balloon Analog Risk Task BART, Lejuez et al., 2004. In this task, volunteers pump a balloon without knowing when it will explode. The more the pump button is pressed, the more points accumulate while at the same time the risk of losing points with a balloon explosion increases. Subjects are thus pressured to decide whether to adopt a risky behavior and keep pumping, or to use a more conservative strategy and stop. tACS was delivered to three groups of healthy volunteers. One group received stimulation over the left prefrontal cortex lPFC, one over the right prefrontal cortex rPFC, and the other received sham stimulation. tACS was delivered online during the task. Stimulation started 5 minutes before the task began and lasted for approximately 10 minutes until the BART was completed. Crucially, active tACS was only delivered at a theta frequency of 6.5 Hz. Sham stimulation involved the same parameters, but was only delivered for 30 s. Results showed a striking effect of lPFC stimulation, whereas rPFC and sham stimulations failed to produce any considerable effect on task performance. More specifically, the increase of sequential losses during tACS stimulation over lPFC suggested that volunteers lost the ability to adjust their actions based on negative feedback. Sela et al. 2012 hypothesized that theta stimulation of the lPFC interfered with volunteers’ performance during the task, making them more inclined to adopt a risky behavior.

via Frontiers | Transcranial Alternating Current Stimulation affects decision making | Frontiers in Systems Neuroscience.