Abstract
We have developed an experimental system for simultaneously recording the locomotor behavior and the neural activities from freely walking insects. The system consists of a motion-tracking subsystem, a motor-driven rotating connector (an active slip ring subsystem), and conventional extracellular recording devices. A pair of linear motion guides is orthogonally arranged to form a 2-D coordinate system above the experimental arena. The head stage of the 2-D guide is equipped with a CCD camera and the active slip ring subsystem. When an animal is detected in the arena by the CCD camera, a programmable logic controller (PLC) sends a feedback signal to the servomotors for the head stage so that the insect is always captured at the center of the image. Thus, the CCD camera continuously follows the animal, and then, the system measures two behavioral parameters, namely, the 2-D coordinates of the animal’s position within the arena and the orientation of the body axis. Electrical signals from neurons are fed to a conventional bio-electrical amplifier through the active slip ring subsystem. The tangling of electrode wires, which is necessarily caused when the animal turns, is automatically compensated for by the active slip ring subsystem. The new system successfully recorded the locomotor and brain neuron activities of field crickets within 12 h.
