Mode changes in activity of single neurons in anterior insular cortex across trials during multi-trial reward schedules.

We previously showed that spike count response distributions in anterior cingulate neurons can be fitted by a mixture of a few Poisson distributions in our reward schedule task. Here we report that the neuronal responses in insular cortex, an area connected to anterior cingulate cortex, can also be nicely fitted. The ratio of Poisson distributions changed with schedule progress, suggesting that neuronal responses in these areas fall into discrete firing modes. More insular neurons show mode changes across the schedules. The selection of firing modes might be related to cognitive processes, but seems independent across the two areas.