Quadrant Occupancy

Left: Visualization of the 4 quadrants in the chamber. Odors are released into the lower right quadrant, colored red. The other three quadrants, all tinged some form of blue, contain no odor. Right: Innate attraction and aversion to a set of odors, as measured using the Quadrant Occupancy metric in the 4 Quadrant Chamber. Adapted from Root et al., Nature (2014).

The Quadrant Occupancy metric measures the degree of aversion or attraction elicited by a given stimulus. Though occupancy in all four quadrants is measured, the lower right quadrant is the main focus, because the stimulus is presented in the lower right quadrant. An aversive stimulus reduces the amount of time the mouse spends in the lower right quadrant, while an attractive stimulus will increase the amount of time the mouse spends in that quadrant. This follows from a simple observation: mice will go towards and spend more time around stimuli they prefer, but avoid stimuli they dislike. The degree of attraction or aversion elicited by the stimulus can be inferred from the magnitude of the occupancy change.

The Quadrant Occupancy metric was originally developed as a custom behavioral measure of attraction and aversion in the first 4-quadrant olfactometer in Vet et al., Physiol. Entomol. (1983). This olfactometer was originally used to measure innate olfactory valence in flies, and was the earliest predecessor for the mouse 4 Quadrant Chamber. The measure was first adapted for use in innate mouse olfaction in Vyas et al., PNAS (2007). It was used in the original paper introducing the mouse 4 Quadrant Chamber, Root et al., Nature (2014).