Influence of Fast-Spiking Prefrontal Neurons on Working Memory Behavior

Working memory is a limited-capacity system for maintaining and manipulating information for recall. Neurons that generate persistent activity in the primate dorsolateral prefrontal and posterior parietal cortex have been shown to be predictive of behavior in working memory tasks, though subtle differences between them have been observed in how information was represented, in some tasks. The role of different neuron types in each of these areas has not been investigated at depth. We thus compared the activity of neurons classified as fast-spiking, putative interneurons, and regular-spiking, putative pyramidal neurons, recorded from the prefrontal and posterior parietal cortex of male monkeys, to analyze their role in the maintenance of working memory. Our results demonstrate that fast-spiking neurons are active during a range of tasks and generate persistent activity during the delay period over which stimuli need to be maintained in memory. Furthermore, the activity of fast spiking neurons, particularly in the prefrontal cortex, is predictive of the subjects recall no less than that of regular-spiking neurons, which are exclusively projection neurons in the cortex and thus capable of transmitting signals from the prefrontal cortex into other areas. Our results shed light onto the fundamental neural circuits that determine subjects memories and judgments.