Figure 5: Location of the lead placement and the “curved lead pathway”.

(a–d) Schematic illustrations of the leads localized in the selected targets. The location of the lead tip of the straight lead was illustrated (a and c). And the location of the lead tip and the point of the curved lead passing through the coronal section 1.08 mm posterior to the bregma (b) or the marker line (2.6 mm mediolateral, black dovetail arrow, (d) were also illustrated. Leads were located within the boundaries of the selected targets in all implanted rats. (e,f) The coronal sections of the brain of a rat in Group C. Two holes were observed at the right GP (figure e, black triangle) and right STN (f) black arrow) respectively, which were caused by an implanted curved lead. (g) The “curved lead pathway” that passing through bilateral STN (black dashed line) could be designed on the coronal section at 3.48 mm posterior to the bregma. It can be observed on the HE stained coronal brain section that the implanted lead (black line) passes the bilateral STN. “Curved lead pathway” crosses the midline, passes through posterior hypothalamus (a) potential target for DBS to ameliorate akinesia in rat^42,43) and the upper edge of third ventricle. IVF: interventricular foramen; ic: internal capsule; cp: cerebral peduncle; 3 V: the third ventricle; PH: posterior hypothalamus; Subl: subincertal nucleus. The scale bars represent 500 micrometers. The number at the bottom of each panel corresponds to the distance from bregma in mm, according to the Paxinos and Watson atlas³⁸. Figures a-d and f were modified from The Rat Brain in Stereotaxic Coordinates of Paxinos and Watson⁴⁰ (reproduced with permission).