A microelectrode array for chronic in vivo single-unit recording in subthalamic nucleus of freely behaving rats

Abstract

Objective To introduce a bundled microelectrode array of chronic in vivo single-unit recording in subthalamie nucleus (STN) of freely behaving rats. Methods STN single cell discharge was recorded by a self-designed bundled microelectrode array.Our microelectrode array design consisted of 3 parts:(1) a 29-guage stainless steel tube was served as a guide tube to facilitate the brain penetration of microwire tips,and as a ground electrode of the brain tissues as well. (2) Five 20μm platiniridium wires were used as recording electrodes and a 50.8 μm stainless steel wire with 1 mm bare tip was employed as local potential reference; all the above resembled a guiding-hand-shaped arrangement in microwire tips,and was fixed by trny plot of carbowax moreover.(3) A male connector with end screw receptors was employed to make the array connection more stable so as to minimize the movement artifacts; six normal rats were implanted with this kind of electrode arrays,and the stability of STN single-unit recording was evaluated in the following 5 weeks. Results Twenty-seven firing units were captured during operation,of which 70.4％ (19/27) survived more than 2 d,and 9 new units were acquired within 5 weeks.No significant linear correlation of peak-to-peak amplitude was noted between each 2 different recording sections (Pearson r=-0.047,P=0.655),and whilst signal-to-noise ratio was stable with significant correlation to peak-to-peak amplitude (r=0.934,P=0.000).More than half of the initial acquired STN units retained more than 3 weeks. And there were more than 75％ r values of waveform similarities large than 0.90 of the same units across different periods. Conclusion This methodology may be appreciated for STN long-term single-unit recording with stable recording quality and favorable cell retained rate. Key words: Subthalamic nucleus; Microelectrode array; Single-unit recording; Freely behaving