LOCAL AND TOP-DOWN REGULATION OF OLFACTORY BULB CIRCUITS

Abstract

The olfactory bulb (OB) is the first place in the brain where chemosensory processing occurs. The neurophysiological mechanisms underlying these processes are mostly driven by inhibition, which is implemented by a large population of local inhibitory neurons, and among them, the granule cell (GCs) is the most prominent type. Local inhibitory interneurons sculpt the coding of output neurons, affecting odor detection, discrimination, and learning. Therefore, the regulation of inhibitory circuits is critical to OB function and fine-tuning OB output. Specifically, inhibitory tone in the OB can be regulated by the dynamic interactions between cell-intrinsic factors affecting neuronal excitability and extrinsic top-down modulation associated with an animal’s behavioral state. Here, I provide new evidence for intrinsic mechanisms governing inhibitory interneuron excitability in the OB and how modulation by noradrenaline works in concert with these intrinsic mechanisms to affect circuit function. This work highlights circuit- and cell-specific differences in noradrenergic modulation with regards to short- and long-term plasticity within OB circuits.