Revisiting the “Paradox of Stereotaxic Surgery”: Insights Into Basal Ganglia-Thalamic Interactions

Basal ganglia dysfunction is implicated in movement disorders including Parkinson Disease, dystonia, and choreiform disorders. Contradicting standard “rate models” of basal ganglia-thalamic interactions, internal pallidotomy improves both hypo- and hyper-kinetic movement disorders. This “paradox of stereotaxic surgery” was recognized shortly after rate models were developed, and is underscored by the outcomes of deep brain stimulation (DBS) for movement disorders. Despite strong evidence that DBS activates local axons, the clinical effects of lesions and DBS are nearly identical. These observations argue against standard models in which GABAergic basal ganglia output gates thalamic activity, and raise the question of how lesions and stimulation can have similar effects. These paradoxes may be resolved by considering thalamocortical loops as primary drivers of motor output. Rather than suppressing or releasing cortex via motor thalamus, the basal ganglia may modulate the timing of thalamic perturbations to cortical activity. Motor cortex exhibits rotational dynamics during movement, allowing the same thalamocortical perturbation to affect motor output differently depending on its timing with respect to the rotational cycle. We review classic and recent studies of basal ganglia, thalamic, and cortical physiology to propose a revised model of basal ganglia-thalamocortical function with implications for basic physiology and neuromodulation.

Comparisons Between First Person Point-of-View 180° Video Virtual Reality Head-Mounted Display and 3D Video Computer Display in Teaching Undergraduate Neuroscience Students Stereotaxic Surgeries

Introduction: Students interested in neuroscience surgical applications learn about stereotaxic surgery mostly through textbooks that introduce the concepts but lack sufficient details to provide students with applied learning skills related to biomedical research. The present study employed a novel pedagogical approach which used an immersive virtual reality (VR) alternative to teach students stereotaxic surgery procedures through the point of view (POV) of the neuroscientist conducting the research procedures.Methods: The study compared the 180° video virtual reality head-mounted display (180° video VR HMD) and the 3D video computer display groups to address the learning gaps created by textbooks that insufficiently teach stereotaxic surgery, by bringing students into the Revinax® Virtual Training Solutions educational instruction platform/technology. Following the VR experience, students were surveyed to determine their ratings of the learning content and comprehension of the material and how it compared to a traditional lecture, an online/hybrid lecture, and YouTube/other video content, as well as whether they would have interest in such a pedagogical tool.Results: The 180° video VR HMD and the 3D video computer display groups helped students attend to and learn the material equally, it improved their self-study, and they would recommend that their college/university invest in this type of pedagogy. Students reported that both interventions increased their rate of learning, their retention of the material, and its translatability. Students equally preferred both interventions over traditional lectures, online/hybrid courses, textbooks, and YouTube/other video content to learn stereotaxic surgery.Conclusion: Students preferred to learn in and achieve greater learning outcomes from both the 180° video VR HMD and the 3D video computer display over other pedagogical instructional formats and thought that it would be a more humane alternative to show how to conduct the stereotaxic surgical procedure without having to unnecessarily use/practice and/or demonstrate on an animal. Thus, this pedagogical approach facilitated their learning in a manner that was consistent with the 3-Rs in animal research and ethics. The 180° video VR HMD and the 3D video computer display can be a low-cost and effective pedagogical option for distance/remote learning content for students as we get through the COVID-19 pandemic or for future alternative online/hybrid classroom instruction to develop skills/reskill/upskill in relation to neuroscience techniques.

3D printed rodent skin-skull-brain model: A novel animal-free approach for neurosurgical training

In neuroscience, stereotactic brain surgery is a standard yet challenging technique for which laboratory and veterinary personnel must be sufficiently and properly trained. There is currently no animal-free training option for neurosurgeries; stereotactic techniques are learned and practiced on dead animals. Here we have used three-dimensional (3D) printing technologies to create rat and mouse skin-skull-brain models, specifically conceived for rodent stereotaxic surgery training. We used 3D models obtained from microCT pictures and printed them using materials that would provide the most accurate haptic feedback for each model—PC-ABS material for the rat and Durable resin for the mouse. We filled the skulls with Polyurethane expanding foam to mimic the brain. In order to simulate rodent skin, we added a rectangular 1mm thick clear silicone sheet on the skull. Ten qualified rodent neurosurgeons then performed a variety of stereotaxic surgeries on these rat and mouse 3D printed models. Participants evaluated models fidelity compared to cadaveric skulls and their appropriateness for educational use. The 3D printed rat and mouse skin-skull-brain models received an overwhelmingly positive response. They were perceived as very realistic, and considered an excellent alternative to cadaveric skulls for training purposes. They can be made rapidly and at low cost. Our real-size 3D printed replicas could enable cost- and time-efficient, animal-free neurosurgery training. They can be absolute replacements for stereotaxic surgery techniques practice including but not limited to craniotomies, screw placement, brain injections, implantations and cement applications. This project is a significant step forward in implementing the replacement, reduction, and refinement (3Rs) principles to animal experimentation. These 3D printed models could lead the way to the complete replacement of live animals for stereotaxic surgery training in laboratories and veterinary studies.

Pathological Changes In The Rats’ Eyes After The Administration Of Oil Machinery Fluid Through Stereotaxic Surgery

Purpose: To achieve a relationship between oil machinery fluid (OMF) and the damage this fluid produces in several eye structures. In neuro-oncology patients, we know there are several parasellar tumors; one of them is the craniopharyngiomas that can produce a cystic structure containing an oily material. It has been denominated as an oil machinery fluid (OMF); this fluid has not yet been widely studied. It is a widely held view that it produces toxic effects in the brain and other structures. This paper aims to see the toxicity of the OMF when administered directly in the brain and the changes produced in the rats’ eyes. Methods: 30 Wistar rats were divided into three groups, control, sham and experimental; the oil machinery fluid was obtained directly from human patients during surgery. The oil machinery fluid was administered to the rat thalamus by stereotaxic surgery. The subjects were under observation after the surgery for five weeks and sacrificed once the observation period ended. Finally, immunohistochemistry was performed on tissue recovered from the eyes. Results: We observed that in the experimental group, there was an increase in glucose levels, the coloration of the eyes changed to a pinkish color, the lenses changed opacity, there were histological changes in the retina, and a reduction of the diameter of the optic nerve in this group in comparison with the control group. Conclusions: All the results observed in this model can be seen in human patients with craniopharyngiomas and diabetes. They are leading us to think that the oil machinery fluid alone can produce ocular changes by damaging several structures by the toxicity created by this fluid.