A multichannel hook electrode for simultaneous recording of up to 12 nerve filaments

This paper describes a simple multichannel hook electrode specially adapted for simultaneous recording from several dorsal root filaments in the cat. The electrode consists of a 3-mm-thick PVC plate and accommodates 12 silver wire hooks placed in notches in the plate. It has a semicircular shape, and the notches are milled radially in the plate. With this electrode we have made successful recordings of single-unit activity from 12 muscle afferents for periods of up to 8 h. In contrast to more rigid and complicated devices, e.g., developed to assess activity of populations of individual neurones from single-channel recordings of multi-unit activity, it also permits selection of the types of afferents to be recorded. The use of this simple device and an appropriate number of amplifiers and window discriminators can greatly enhance the quality of studies on populations of afferents in animals and may also decrease the number of laboratory animals needed.