Pharmacologically and Electrically-induced Network-wide Activation of Olfactory Bulb with Large-scale Biosensor

The olfactory bulb is a multi-layered structure that dynamically tunes high-dimensional olfactory information from the olfactory epithelium and conveys spatiotemporal codes to higher-order areas of the brain. Available techniques lack adequate spatiotemporal resolution, challenging understanding of the dynamic mechanisms underlying information coding in the olfactory bulb (OB) circuitry. Large-scale ex-vivo recordings from OB interconnected layers were recently obtained using high-density CMOS-based biosensors, allowing network-wide investigations of OB electrophysiological properties to uncover layer-specific firing patterns and their dynamical features. Here, we examine changes in simultaneously recorded multi-unit spiking activity and local field potential oscillations focusing on three OB layers in different drug-induced activations. Furthermore, electrically evoked responses of OB circuitry were also analyzed, as delivery of electrical stimuli to the glomerulus layer elicits a response that mimics the natural activation following a sensory input. Our results delineate that this approach effectively describes the spatiotemporal dynamics of OB circuitry. It can be further exploited to investigate the computational implications of large-scale activity patterns in olfactory processing.