BOWIe: Wireless Headstage for Optical Stimulation in Closed-Loop Optogenetics Experiments in Freely-moving Rodents

Abstract

Optogenetics is an invaluable technique in neuroscience to study brain circuits, but conventional optogenetic systems use tethered approaches to deliver light to the brain which can hinder natural behavior. Optoelectronic advances led to the development of wireless optical stimulators for optogenetics experiments, but most reported devices have low widespread use due to complex builds and reduced versatility, which has also limited their integration in closed-loop systems. Here, we developed BOWIe, a battery-powered, low-weight, wireless headstage for photostimulation in optogenetics experiments with rodents, especially designed for simple integration in multiple behavioral setups, including those requiring closed-loop operation. BOWIe is based on a Bluetooth-Low Energy system-on-a-chip that allows simultaneous control and communication capabilities with a reduced number of components, and can be paired with an Arduino-based transmitter for simple integration in any behavioral paradigm using analogue or digital triggers. Two modes of optical stimulation are possible, either with ferrule-coupled optical fibers or LED neural probes, which permit adapting the headstage according to material availability or experimental demands. A user-friendly app was also developed to simplify headstage pairing, definition of stimulation parameters, and protocol design. BOWIe was validated in two behavioral paradigms, including in a closed-loop experiment using computer vision, Bonsai RX, and Deeplabcut Live to track behavioral parameters online and remotely trigger photostimulation upon detected events. BOWIe's modular design and flexible integration with behavioral setups make it a practical tool for in vivo experiments with optogenetics.