In the SEF population, this disappearance and resurgence of CH > CL activity might be explained by opposing dynamics of CH > CL and CH < CL neurons. The individually significant Vorinostat CH > CL neurons sustained their signal through the entire bet stage (Figure 5A), but the CH < CL neurons were transiently active in the late interstage and early bet stage (Figure 5B), so they may have effectively nullified the CH > CL signal during that time at the population level. Many neurons in the SEF encode reward anticipation (Roesch and Olson, 2003; So and Stuphorn, 2010).

In our experimental design, reward amounts were determined entirely by behavior: the decision and the bet. We could not know what reward amounts the monkeys expected on given trials, but it is likely that they placed high bets in anticipation of high reward and low bets in anticipation of low reward. If our SEF neurons represented reward anticipation, this might explain the higher firing rates in CH versus CL trials and IH versus IL trials. Quantitatively, the reward GABA inhibitor review anticipation hypothesis predicts that activity should be equal for all trials in which the same bet was made after different decisions: firing rates should be indistinguishable between CH and IH trials

and between CL and IL trials. We found that, to the contrary, SEF activity strongly differentiated between CH and IH trials and between CL and IL trials through the decision

stage and Cediranib (AZD2171) into the bet stage. As with our usual analyses, we considered trials for which targets were located within, and saccades were directed into, the contralateral field. During the decision stage ( Table S9), the CH-IH difference in population activity began in the visual-1 epoch and lasted through the interstage epoch. In the subsets of neurons with significant activity in each epoch, the same pattern of results was observed with the exception of the presaccadic-1 epoch. SEF activity also was different in the decision stage between CL and IL trials. As a population, the difference was significant during the delay and interstage periods. For the subsets, CL-IL firing rates were different from the visual-1 epoch through the interstage epoch, except in the presaccadic-1 epoch. Thus, although we would not rule out effects of reward anticipation during the decision stage, we found little evidence for it. During the bet stage (Table S10), SEF population activity became more similar between CH and IH trials and between CL and IL trials; differences in activity between these trial outcomes diminished and eventually ceased. This implies that neuronal correlates of reward anticipation may have contributed more to SEF population activity near the end of the trial. On a related note, SEF neurons are known to modulate with reward delivery (Stuphorn et al., 2000).