A new intraretinal recording system with multiple-barreled electrodes for pharmacological studies on cat retinal ganglion cells

To overcome technical difficulties associated with in vivo intraretinal rec ordings of cat retinal ganglion cells (RGCs) with multiple-barreled electro des, we developed a new guide-trocar system that consisted of a small-diame ter and large-diameter pipes. We also improved the method to construct tung sten-in-glass multiple-barreled electrodes suitable for intraretinal record ing from RGCs. Only the small-diameter pipe was inserted into the eye ball through the sclera, through which only the taper part of a multiple-barrele d electrode pass. The large-diameter pipe stably held the electrode at its trunk and remained outside the eye ball. Insertion of only the small-diamet er pipe minimized damages in the eye ball and prevented the eye ball moveme nts while positioning the electrode. The system allowed us to keep the reco rdings stable for more than 1 h. Iontophoretically applied L-glutamate succ essfully activated RGCs of both X and Y types in the cat retina. (C) 2000 E lsevier Science B.V. All rights reserved.