Larva in the loop, a closed loop machine interface system for Danio rerio larvae

Abstract

The optokinetic response (OKR) in Zebrafish (Danio Rerio) had been characterized for its robust response to visual stimuli. Expanding on these works, we developed a novel closed loop control schema to drive a robot utilizing the OKR of Zebrafish larvae. Our system keeps the body of a larva constrained via a novel agarose mold holder that allows for eye movement and vision. The larva is then put under a microscope camera and processed through computer vision to track its eyes via ellipse fitting. Relative eye angle data is then parsed through an algorithm and used to send movement signals to a robot on a lined track. Simultaneously, the robot returns its relative position with respect to the line and converts that information into an OKR stimulation animation which is displayed on an LCD screen in the ventral plane of the larva, thus closing the loop. Through this work we show the capability of larvae OKR to keep a robot on a linear track after an initial oblique entrance to the line. This work displays the potential of our system and how it can pave the way to a Zebrafish Brain-Machine Interface.