Microiontophoretic study of depressant amino acids and the specificity of their antagonists.

1. The e.e.g. potentials are picked up by stainless steel screws inserted in the skull and are led via a multi-channel miniature electrical connector (ITT Cannon, Basingstoke) to the recorder. 2. The intraventricular cannula described by Hayden, Johnson & Maickel (1966) for use in the rat proved equally suitable for the rabbit. Constructed of Perspex, its lighter weight compared with that of commercially available cannulae is advantageous. Confirmation of the implantation site (lateral ventricle) and the patency of the cannula after implantation was readily determined by withdrawing cerebrospinal fluid into a sterile Hamilton syringe (10 I.4, 701 RN). 3. Behavioural activity was recorded simultaneously with the e.e.g. recordings on a polygraph by means of an ultrasonic Activity Monitor (C. F. Palmer, High Wycombe, Bucks.). The ultrasonic transducers were mounted vertically above the box in which the animal was placed. The screws, connector and cannula were attached during halothane anaesthesia using standard aseptic techniques. After recovery animals prepared in this way have shown no overt deviation from normal behaviour and have remained healthy giving good e.e.g. records for up to a year.