Tectal Multielectrode Recordings of the Visual Response in Columba livia

Extracellular recordings were performed using two arrays of regularly spaced tungsten microelectrodes (4x4 and 4x8, 1-2 MOhms, 125 µm thick, 250-300 µm electrode tip separation (Microprobes, Gaithersburg, MD)) and a RHD2000-EVAL multi-channel amplifier (Intan Technologies, Los Angeles, CA).
Each array was inserted at approximate 500 µm depth in the tectum. A silver wire was implanted in the bone in contact with the saline as a reference electrode. Neural signals were amplified, band passed between 10 Hz and 10 KHz and digitized at 20 KHz.