A technique for EEG recording in the awake parakeet

Abstract

the proper stereotaxic instrument for thespecies, (2) some degree of surgical sophistication,(3) sterile surgical conditions, (4) an accurate atlas of thespecies' brain and cranial bones, and (5) an anestheticduring the recording session. One of the standardtechniques used to circumvent some of these problems isto use stainless steel screw electrodes that are screwedinto the skull and held by dental acrylic. However, theparakeet skull is extremely thin and fragile-asis the casewith most small birds. This precluded the use of screwelectrodes and prompted the development of alternativeand somewhat simpler methods for attaching electrodesto the parakeet. These procedures may be ofparticularvalue in view of the recent interest in avian sleepprocesses and sensory processes (Van Twyver & Allison,1972; Dooling & Saunders. 1974).The skin covering the underside of the lower beak inthe parakeet is thin. This enables one to insert a 30-ga,Kynar-coated solid wire through the underside of themandible into the oral cavity and wrap it tightly aroundthe lateral portion of the lower beak. (See lower half ofFigure 1.) The length of wire wrapped around the beakis stripped to permit good electrical contact. Thisprocedure is applied to both sides of the parakeet'sbeakto provide both a ground and a reference electrode. Theinsulated portions of these beak electrode wires are ledto the back of the bird'shead, pulled taut, and threadedthrough the side holes ofa standard three-poletransistorplug as indicated in the upper half ofFigure I.A number of types of skull electrodes have been usedin combination with these beak electrodes. Theseinclude a 2 mm in diam coil of silver wire or a disk ofsilver foil, dental screws, and inverted wire nails.Regardless of the electrode type, it is attached to theskull using the following general procedures.The bird's head is cleaned with alcohol, and anincision is made along the medial axis of the scalpextending from the cere about 2 ern posteriorly. Theskin is pulled back, the skull surface wiped clean with acotton swab, and the electrode cemented to the skullwith conventional dental acrylic. The electrode lead isthen led to the third pole of the transistor plug. The