Implant of flexible probes - Supplemental

long term functional and reliable coupling between neural tissue and implanted microelectrodes is the key issue in acquiring neural electrophysiological signals or therapeutically excite neural tissue. The currently often used rigid micro-electrodes are thought to cause a severe foreign body reaction resulting in a thick glial scar and consequently a poor tissue-electrode coupling in the chronic phase. We hypothesize, that this adverse effect might be remedied by probes compliant to the soft brain tissue, i.e. replacing rigid electrodes by flexible ones. Unfortunately, this flexibility comes at the price of a low buckling force, which makes targeted low trauma implantation very challenging. In this study, we demonstrate an adaptable and simple method to implant extremely flexible microprobes even to deep areas of rat’s brain. Successful implantation of flexible probes is achieved by rod supported stereotactic insertion fostered by a hydrogel cushion on the exposed skull. We were thus able to reliably implant very flexible micro-probes in a high number of rats as deep as the rodent's subthalamic nucleus. This work describes in detail the procedures and steps needed for minimal invasive, but reliable implantation of flexible probes. Supplemental video material is available.