Custom-Built Operant Conditioning Setup for Calcium Imaging and Cognitive Testing in Freely Moving Mice

Abstract

Operant chambers are widely used in animal research to study cognition, motivation, and learning processes. Paired with the rapidly developing technologies for brain imaging and manipulations of brain activity, operant conditioning chambers are a powerful tool for neuroscience research. The behavioral testing and imaging setups that are commercially available are often quite costly. Here, we present a custom-built operant chamber that can be constructed in a few days by an unexperienced user with relatively inexpensive, widely available materials. The advantages of our operant setup compared with other open-source and closed-source solutions are its relatively low cost, its support of complex behavioral tasks, its user-friendly setup, and its validated functionality with video imaging of behavior and calcium imaging using the UCLA Miniscope. Using this setup, we replicate our previously published findings showing that mice exposed to social defeat stress in adolescence have inhibitory control impairments in the Go/No-Go task when they reach adulthood. We also present calcium imaging data of medial prefrontal cortex (mPFC) neuronal activity acquired during Go/No-Go testing in freely moving mice and show that neuronal population activity increases from day 1 to day 14 of the task. We propose that our operant chamber is a cheaper alternative to its commercially available counterparts and offers a better balance between versatility and user-friendly setup than other open-source alternatives.

Significance Statement

Operant conditioning chambers are widely used in neuroscience research, but commercially available operant setups are often costly. Here, we describe the construction of an open-source, low-cost operant conditioning setup which can be constructed in a few days using widely available materials. Using this setup, we replicate our previous findings showing that exposure to social defeat stress in adolescence impairs inhibitory control in adulthood. We also pair our setup with in vivo calcium imaging, and we show that we can record calcium activity from individual neurons in the medial prefrontal cortex (mPFC) of freely moving mice while they carry out a cognitive task. Our custom-built operant conditioning setup is a useful tool to study the neurobiology of both adaptive and pathologic behavior.