IMPROVEMENTS FOR EXTRACELLULAR RECORDINGS IN THE MEDIAL PREFRONTAL CORTEX OF FREELY MOOVING RATS

01/30/2020

Zoltán Petykó¹, Kázmér Karádi², Zsolt Kisander², László Lénárd¹, Kálmán Máthé³, Rita Gálosi¹

¹ Institute of Physiology, Medical School of University Pécs, Pécs; 2Institute of Behavioural Sciences, Medical School of University Pécs, Pécs; 3Faculty of Engineering and Information Technology, University of Pécs

In our experiments we investigated the neuronal activity of the rat medial prefrontal cortex (mPFC). The mPFC is a relatively narrow area for multielectrode recordings. In order to increase electrode density and to decrease microdrive size, we redesigned the fabrication of wire electrodes, electrode interface board, PCB (printed circuit board) microdrive and tether cable. Instead of our earlier 8 screw microdrive we constructed a one-screw microdrive. In that microdrive electrodes cannot be moved individually, but the electrode density was increased and the driver’s height was reduced. The total implanted height was less than 20 mm, with connected 32 channel amplifier 25 mm. In our test recordings 8 stereotrodes constructed of 12 m tungsten wires were passed through a 10 mm long, 350 m diameter silica tube and glued into the tube. The free ends of the wires were immersed in 60 C polyethylene glycol (Mn 10000), which protected the electrodes during implantation. The new interface board was with lover height, but large pads allow easy soldering of electrode wires. The wires in the tether cable were directly soldered to the new designed headstage amplifier, this results a small, low-built amplifier (12 mm). Using this new design 230 neurons were recorded during 38 experimental sessions. Recording of the neurons was stable for at least 2 hours. Some neurons could be stably recorded for up to 2 weeks. Supported by EFOP-3.6.1-16-2016-00004