Gamma and Beta Band Oscillation in Working Memory given Sequential or Concurrent Multiple Items: A Spiking Network Model.

Working memory can maintain sequential and concurrent information, and the load enhances the gamma-band oscillation during the delay period. To provide a unified account for these phenomena in working memory, we investigated a continuous network model consisting of pyramidal cells, high-threshold fast-spiking interneurons (FS), and low-threshold non-fast-spiking interneurons (nFS) for working memory of sequential and concurrent directional cues. Our model exhibits the gamma (30-100Hz) and beta (10-30Hz) band oscillation during the retention of both concurrent cues and sequential cues. We found that the beta oscillation results from the interaction between pyramidal cells and nFS, whereas the gamma oscillation emerges from the interaction between pyramidal cells and FS due to the strong excitation elicited by cue presentation, shedding light on the mechanism underlying the enhancement of gamma power in many cognitive executions.We constructed a spiking network to perform working memory tasks with sequentially or concurrently presented items. The model exhibits the coexistence of beta (10-30Hz) and gamma (30-100Hz) band oscillations during the delay period. We found that gamma and beta-band oscillations recruit separate neural circuits. The low-threshold nFS neurons are involved in the beta-band oscillation, whereas the high-threshold FS neurons are involved in the gamma-band oscillation. Our results shed light on the well-known phenomenon that cognitive tasks enhance gamma-band oscillations.