Abstract
Carbon fibers are an ideal material for constructing multi-channel extracellular recording arrays. We have been working to construct 16-channel carbon fiber electrodes to record the activity of cells in the ferret LGN. An impedance below 4 MΩ was used as the standard for success. At the start of the process, very few channels met this goal. We implemented new methods for constructing and testing electrodes, and our success rate was brought up to an average of 83% (13 out of 16 channels in 19 electrodes). The new methods include an updated jig design, an improved silver-printing procedure, and the addition of a gold electroplating step to treat the recording tips of the carbon fibers. The electrodes constructed with the revised methods have been used to record from ferret V1 cortex, and have shown recorded spike amplitudes ranging from -150 to -300 µV. These results confirm the capability of our carbon fiber electrodes to record neural activity. Our construction methods provide a solid foundation that equips the lab to make future adjustments to meet the goal of producing electrodes with a higher density of carbon fibers and with the necessary robustness to record in deeper brain regions like the LGN.