American University’s Computational and Systems Neuroscience Lab, run by Dr. Mark Laubach, aims to create a fully open-source 3D-printed syringe pump in collaboration with Linda Amarante, a Behavior, Cognition and Neuroscience (BCaN) PhD candidate, and Jonathan Newport, the lab director of the Department of Physics.
Syringe pumps are useful equipment for scientific research labs and are used across many science fields to deliver precise fluid volumes. In behavioral neuroscience, syringe pumps are used to deliver rewarding fluids to rodents. Commercially sold devices are expensive and often not customizable. Designs for open-source syringe pumps have emerged over the past couple of years, and the one designed by the AU team is special because it can deliver different corresponding fluid volumes in equal amounts of time.
Meagan Mitchell, a sophomore neuroscience major, has always been interested in biology and chemistry. She found her place at AU in the neuroscience major, directed by Dr. Catherine Stoodley, after taking introductory neuroscience courses in her freshman year.
In the future, Mitchell is interested in doing research and applying to medical school. She was introduced to the project in fall 2018, after taking NEUR-380, Computational Methods in Brain and Behavioral Sciences, with Dr. Laubach. The class introduces students to basic programming and how computers and software applications are used in neuroscience research. Visiting the Design and Build Lab (DaBL) was a requirement for this course, and Mitchell garnered an interest in 3D printing.
Mitchell’s newly acquired 3D-CAD and CAM skills enabled her to join this project and replicate an open-source design for a 3D-printed syringe pump. After presenting her work on the syringe pump at the 2019 Robyn Rafferty Mathias Student Research Conference, she received the award for best poster presentation in the natural sciences by a freshman or sophomore.
Josh Wilson, a third year neuroscience major, began his time at American University without a declared major. Early in his sophomore year, he met Kristof Aldenderfer, an adjunct physics professor and manager of DaBL. Wilson made an immediate connection to the concept of rapid prototyping and began working at DaBL.
Since then, he has been able to experience a new side of science. He learned the basics of electronics, 3D-printing, and design through Fusion 360, an opensource 3D-CAD software, as well as other various technical skills.
After declaring as a neuroscience major, Wilson went on to take NEUR-220, “The Neuron,” with Prof. Laubach. He was able to get a glimpse into how neuroscience could be combined with other various skills and interests he had accumulated to that point. Wilson joined Prof. Laubach’s lab and immediately found a place to implement some of his new skills. His first project was to assist Amarante and Newport in creating the printed circuit board that would go onto the syringe pump. He also helped another PhD candidate, Kyra Swanson by 3D printing various parts for her experiments.
The original design for this syringe pump came from a design posted on OpenBehavior, an online repository of open-source tools for behavioral neuroscience research managed by Dr. Laubach, Dr. Alexxai Kravitz from Washington University in St Louis, and two BCaN PhD students in the Laubach Lab: Amarante and Samantha White.
Modifications were made to the original design to meet the needs of research in the Laubach Lab. Mitchell modified three of the parts to accommodate large 60 cc syringes using Fusion 360. Newport created a circuit board with an Arduino teensy microcontroller and motor driver that is programmed to adjust for different volumes, flow rates, and timing.
Mitchell and Wilson worked with Newport to manufacture the circuit board by soldering the components together and connecting it to the motor of the 3D-printed pump. This modification allows for three different volumes of fluid to be delivered across the same time frame by adjusting the motor's velocity and acceleration through the teensy. This modification is important because it keeps the timing of the reward delivery constant, which is crucial in behavioral tasks, while also simplifying the necessary components.
The advantages to this syringe pump make it suitable for scientific research. A major problem that is solved is the dissociation of time from the size of the reward. In previous studies with traditional syringe pumps, if a larger reward was given, the pump had to remain on for a longer time (i.e., 1 drop of fluid comes out faster than 3 drops of fluid). As a result, it has not been resolved if brain cells that have been called “reward neurons” encode the magnitude of the fluid or the duration of the fluid delivery. The novel device developed by Mitchell, Wilson, and the AU team separates timing and reward delivery and has already enabled new studies on reward coding by the prefrontal cortex in Amarante’s PhD studies.