Abstract
Cognitive functions such as working memory require integrated activity among different brain regions. Notably, entorhinal cortex (EC) activity is associated with the successful working memory task. Olfactory bulb (OB) oscillations are known as rhythms that modulate rhythmic activity in widespread brain regions during cognitive tasks. Since the OB is structurally connected to the EC, we hypothesized that OB could modulate EC activity during working memory performance. Herein, we explored OB–EC functional connectivity during spatial working memory performance by simultaneous recording local field potentials when rats performed a Y-maze task. Our results showed that the coherence of delta, theta, and gamma-band oscillations between OB and EC was increased during correct trials compared to wrong trials. Cross-frequency coupling analyses revealed that the modulatory effect of OBs low-frequency phase on EC gamma power and phase was enhanced when animals correctly performed working memory task. The influx of information from OB to EC was also increased at delta and gamma bands within correct trials. These findings indicated that the modulatory influence of OB rhythms on EC oscillations might be necessary for successful working memory performance.
Highlights
Working memory is a workspace for temporary storage and active manipulating information for ongoing decision-making [1,2,3]
We investigated the Olfactory bulb (OB)–entorhinal cortex (EC) functional connectivity during the working memory task by simultaneous recording local field potentials (LFPs) when rats spontaneously alternated in the Y-maze
We observed that the OB–EC coherence in the delta and theta range during correct trials was significantly higher than wrong trials (p < 0.05; Fig. 2a–c)
Summary
Working memory is a workspace for temporary storage and active manipulating information for ongoing decision-making [1,2,3]. Successful working memory performance depends on organized communication between brain regions [1,2,3]. The entorhinal cortex (EC) is a part of the medial temporal lobe system, positioned as a ‘gateway’ between neocortical areas and the hippocampal memory system [4]. It has been shown that EC is acting as a temporal buffer of incoming information to the hippocampus [5]. EC ablation disrupts the working memory performance [6,7,8]. EC is likely pivotal for successful working memory performance [9]
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