Establishment Of Rhesus DBS Model Of Bilateral Nucleus Accumbens

Background and objective:Rhesus monkeys of nonhuman primate are important experimental animals to study brain functions and they are also ideal animal models to study the mechanism and application of deep brain stimulation(DBS).The fuction of DBS has close relationship with the location of electrode,and the effect of it depends on the exact location of the corresponding target. Therefore, accurate orientation of deep brain nuclus is very important while rhesus are used in DBS related research. However, the orientation of deep brain nuclus of rhesus monkeys is mainly based on the coordinates of the monkey brain stereotactic atlas in the current experiments.The defect of this approach is obvious, because different strains and individuals of monkeys have diffences with the same coordinates.Even different monkey brain atlas have different coordinates of the same nucleus, this is related to different samples that are used in atlas.Clinical stereotactic technology has already achieved image assisted orientation of the targets, while dedicated equipments are applied to DBS implantation. However, the skull of rhesus monkeys is much smaller than humans', clinical frame stereotactic surgery system can not be directly used in experimental animals. Therefore, we designed and produced a stereotactic head-ring adapter, the size of which is between the skull of rhesus and frame,and the adapter can be tightly fixed on the skull of rhesus and the frame.The introduction of the adapter is equivalent to the expansion of the rhesus monkey's head circumference, that makes applying MRI guided frame stereotactic surgery system to rhesus possible.In this study, the nucleus accumbens as representative of deep brain nucleus,accurate and individual orientation of deep brain nucleus of rhesus and implantion of DBS electrodes to model while using the method mentioned before was discussed.MethodsFirst step: Skulls of two rhesus were fixed on CRW-FN stereotactic head frame by self-made adapter, 1.0T thin slice MRI scan was performed, and locations were orientated while coordinates of the bilateral accumbency were calculated consulting MRI and pathological atlas of rhesus,then NAc were lesioned; After 1 week,3.0T thin slice MRI scan were performed, positions of the lesion were observed. Second step: Skulls of four rhesus were fixed on CRW-FN stereotactic head frame by self-made adapter, 1.0T thin slice MRI scan was performed, and locations were orientated while coordinates of the bilateral accumbency were calculated consulting MRI and pathological atlas of rhesus,then electrodes were implanted and fixed on Titanium mesh,and the rest of the exlectrodes were planted at the subcutaneousness of neck and back; After 1 week,1.0T thin slice MRI scan were performed, positions of the electrodes were observed, and distance between the ends of 8 DBS electrodes and the the intended target of the ipsilateral accumbens was measured by a radiologist.ResultsA method had been designed to accurately orientate deep brain nucleus of rhesus, four Rhesus were successfully implanted with bilateral electrodes, no bending and shift was showed on postoperative MRI, the distance between the ends of lesion and the accumbens was 0.65±0.35mm in forward and back direction, and distance in the left and right direction was 0.43±0.17mm. the distance between the ends of electrodes and the accumbens was 0.64±0.28mm in forward and back direction, and distance in the left and right direction was 0.34±0.17mm.ConclusionsBy using self-made adapter, clinical MRI guided stereotactic surgery system can be used on Rhesus to achieve individual and accurate orientation of deep brain nuclei and DBS implantation.By using self-made adapter, clinical MRI guided stereotactic surgery system can be used on Rhesus to achieve individual and accurate orientation of deep brain nuclei and successful establishment of rhesus DBS model of nucleus accumbens...