Hello! We are happy to announce our first workshop of the new academic year! This time we will teach you how to use the *Bonsai* reactive programming language. Many experiments require us to synchronize multiple data streams— from cameras, sensors, microscopes—precisely deliver stimuli, and, quite often, do everything in a *closed-loop* setting. The fact that different devices use different software doesn’t make this task easier. One of the best—and open—solutions to these challenges is *Bonsai*, a reactive programming language that allows you to collect data from multiple systems, from calcium imaging through sound recordings to sensors, and to control output devices—such as feeders, motors, or stimulus delivery systems—to build *closed-loop* paradigms. It is easy to learn, implement, and is robust. During our workshop, we will introduce the basic logic of Bonsai; cover loading and saving data; working with a camera to track animals; and the basics of closed-loop experiments. We will also cover using Arduino alongside Bonsai to control experimental equipment and to save data from your sensors. *Requirements:* A Windows computer and a webcam. The workshop will take place on *Oct 17, 9:45 AM–5:00 PM* at *COS, Heidelberg Institute*. Please find more info and the registration form here: https://openlabhd.org/2025/09/30/bonsai-programming-workshop-oct-17th/ With best wishes, *Mateusz Kostecki* -- --- Mateusz Kostecki PhD Student Knapska Laboratory Nencki Institute 02-093 Warsaw, Pasteura 3, Poland https://twitter.com/mtkostecki https://evolvingbehavior.blog/