  Humans often make decisions which maximize an internal utility function. For
example, humans often maximize their expected reward when gambling and this is
considered as a "rational" decision. However, humans tend to change their
betting strategies depending on how they "feel". If someone has experienced a
losing streak, they may "feel" that they are more likely to win on the next
hand even though the odds of the game have not changed. That is, their
decisions are driven by their emotional state. In this paper, we investigate
how the human brain responds to wins and losses during gambling. Using a
combination of local field potential recordings in human subjects performing a
financial decision-making task, spectral analyses, and non-parametric cluster
statistics, we investigated whether neural responses in different cognitive and
limbic brain areas differ between wins and losses after decisions are made. In
eleven subjects, the neural activity modulated significantly between win and
loss trials in one brain region: the anterior insula ($p=0.01$). In particular,
gamma activity (30-70 Hz) increased in the anterior insula when subjects just
realized that they won. Modulation of metabolic activity in the anterior insula
has been observed previously in functional magnetic resonance imaging studies
during decision making and when emotions are elicited. However, our study is
able to characterize temporal dynamics of electrical activity in this brain
region at the millisecond resolution while decisions are made and after
outcomes are revealed.
