How are uncertainty, reward and risk encoded in networks of cells? How is information about uncertainty and reward distributed in the fronto-parietal network?

Experimental preparation: Two male macaque monkeys (Macaca fascicularis) were prepared for The informational task based on a paradigm that we developed in the lab (Peck et al., 200; Foley et al., 2014a) where visual cues predict a forthcoming reward but do not allow the monkeys to act so as to maximize the rewards. That is, the cues have value only in updating predictions (“learning”) but not in guiding actions. Multi-electrode recording system: We used Utah arrays ( Microsystems, LLC) implanted on the cortical surface - areas 7a and the dorsolateral prefrontal cortex (dlPFC) - and multi-contact “U-probes” to reach sulcal areas - the frontal eye field (FEF) and the lateral intraparietal area (LIP). The goal is to examine the dynamics of neuronal populations that cannot be inferred from individual cells but are likely to define cognitive states. Statistical analysis: We used power scalograms to limit our analysis in a time-frequency window. We also used regression analysis to find the linear effect of our task variables such as expected value of the reward and probability associated with a cue on the LFP powers.

So far, we have found behavioral evidence suggesting that the monkeys calculate the reward uncertainty and the expected value of the reward. We have also found neural correlates of the encoding of previous trial and current trial reward value in the LFP traces. This encoding differs when the cue appears in the left side of the screen compared to the trials in which the cue appears in the right side. Single neuron analysis revealed that some neurons encode the cue location in both frontal and parietal cortex, however, we couldn't find precise encoding of expected value of the reward in single neurons.

This research is still ongoing and we have not reached to the final conclusion yet.