Open-Source JL Olfactometer for Awake Behaving Recording of Brain Activity for Mice Engaged in Olfactory Tasks

Automated olfactometers are used to study brain function in rodents engaged in olfactory behavioral tasks. In this chapter, we describe the JL olfactometer, an open-source olfactometer developed by our laboratory to record neural activity through electrodes or microscopic imaging in mice engaged in a variety of olfactory behavioral tasks. The JL olfactometer monitors the licks the mouse makes on a lick spout located within an odorant port and controls odorant application and delivery of water reward through the opening and closing of valves. Neural activity is recorded in head-fixed mice using multiphoton microscopy or neuropixels and in freely behaving mice using miniature microscopes, tetrodes, or multielectrode arrays. Mouse movement is recorded with a video camera. An INTAN RHD2000 evaluation system monitors the activity of the JL olfactometer and records other inputs such as sniff recording and signals synchronizing the video camera and other instruments such as the multiphoton microscope. The design is open source and the MATLAB code can be modified to suit research goals. We discuss the use of olfactometry in the study of odorant perception in health and disease.