Spatial working memory enhances gamma oscillations in rodent olfactory bulb and medial prefrontal cortex

Abstract

Spatial working memory (SWM), a specialized form of working memory that temporarily encodes and retains spatial information, is fundamental to guide animal behaviors, yet our current knowledge of its circuit mechanisms remains far from known. Since, olfactory bulb (OB) and medial prefrontal cortex (mPFC) are critical brain structures for a wide range of cognitive behaviors, we hypothesized that the OB-mPFC circuit gamma oscillations might support rodent SWM processing. Our results show that SWM enhances regional low (30-60 Hz), but not high (60-100 Hz), gamma oscillations in both OB and mPFC, in correlation with the animals behavioral performance. Additionally, the OB-mPFC gamma band functional connectivity is strengthened by SWM. Moreover, we find that mPFC gamma oscillatory information transfer to OB supports the animals SWM performance. We also show that OB low gamma oscillations are modulated by mPFC delta phase, which further signifies the roles of mPFC feedbacks to shape OB gamma activity during SWM. These results suggest that OB-mPFC circuit gamma rhythms underlie SWM processing, and point towards possible mechanisms for cognitive disorders.