Fast-spiking neurons in monkey orbitofrontal cortex underlie economic value computation

Inhibitory interneurons are fundamental constituents of cortical circuits that process information to shape economic behaviors. However, the role of inhibitory interneurons in this process in the core cortical reward region, the orbitofrontal cortex (OFC), remains elusive. Here, we show that presumed parvalbumin-containing GABAergic interneurons (fast-spiking neurons, FSNs) differ from regular-spiking pyramidal neurons (RSNs) in computing economic value. While monkeys perceived a visual lottery for probability and magnitude of rewards, identified FSNs constituted 12% of OFC neurons and showed high-frequency firing rates and wide dynamic ranges, which are both key intrinsic cellular characteristics regulating cortical computation. We found that FSNs showed stronger neural modulation compared to RSNs in signaling probability and magnitude information. Unambiguously, both neural populations signaled the expected values, but FSNs processed the reward information more strongly under the influence of dynamic range. Thus, stronger FSN signals may appear with wider dynamic range for expected value computation.