The role of spatial ability in mixed reality learning with the HoloLens.

The use of mixed reality in science education has been increasing and as such it has become more important to understand how information is learned in these virtual environments. Spatial ability is important in many learning contexts, but especially in neuroanatomy education where learning the locations and spatial relationships between brain regions is paramount. It is currently unclear what role spatial ability plays in mixed reality learning environments, and whether it is different compared to traditional physical environments. To test this, a learning experiment was conducted where students learned neuroanatomy using both mixed reality and a physical plastic model of a brain (N = 27). Spatial ability was assessed and analyzed to determine its effect on performance across the two learning modalities. The results showed that spatial ability facilitated learning in mixed reality (ß = 0.21, P = 0.003), but not when using a plastic model (ß = 0.08, P = 0.318). A non-significant difference was observed between the modalities in terms of knowledge test performance (d = 0.39, P = 0.052); however, mixed reality was more engaging (d = 0.59, P = 0.005) and learners were more confident in the information they learned compared to using a physical model (d = 0.56, P = 0.007). Overall, these findings suggest that spatial ability is more relevant in virtual learning environments, where the ability to manipulate and interact with an object is diminished or abstracted through a virtual user interface.

Exploring the Role of xR in Visualisations for Use in Medical Education.

Emerging technologies have the potential to transform our approach to medical education. A goal in this chapter is to inspire researchers, educators and scholars in the bio-medical visualisation field who can benefit from integrating wearable Augmented Reality (AR) technologies, like the HoloLens into their existing teaching and learning environments. We draw from case studies, existing research and the educational technology literature, to propose the design of purposeful learner-centered experiences that might benefit from wearable AR technologies in the classroom.

Integrated virtual and cadaveric dissection laboratories enhance first year medical students' anatomy experience: a pilot study.

BACKGROUND: Radiology integration into medical anatomy courses is well established, but there is a paucity of literature on integrating virtual dissection into cadaveric dissection laboratories. Virtual dissection is the digital dissection of medical images on touchscreen anatomy visualization tables. The purpose of this pilot study was to investigate the feasibility of integrating virtual dissection into a first-year medical cadaver-based anatomy course and to assess students' overall attitude towards this new technology. METHODS: All students in first-year medicine at a single medical school participated in this study (n = 292). Six virtual dissection laboratories, which focused on normal anatomy, were developed and integrated into a cadaver-based anatomy course. The virtual dissection table (VDT) was also integrated into the final anatomy spot exam. Following the course, students completed a short evidence-informed survey which was developed using a theoretical framework for curriculum evaluation. Numerical data were tabulated, and qualitative content analysis was performed on students' unstructured comments. RESULTS: The survey response rate was 69.2% (n = 202/292). Most (78.7%) students reported that virtual dissection enhanced their understanding of the cadaveric anatomy and the clinical applications of anatomy. Most (73.8%) students also felt that the VDT was an effective use of the laboratory time. Thirteen narrative comments were collected, most of which (61.5%) identified strengths of the curriculum. CONCLUSIONS: In this pilot study, students perceived that their learning was enhanced when virtual dissection was combined with a cadaver-based anatomy laboratory. This study demonstrates that there is potential for virtual dissection to augment cadaveric dissection in medical education.

The influence of brain iron on myelin water imaging.

With myelin playing a vital role in normal brain integrity and function and thus in various neurological disorders, myelin sensitive magnetic resonance imaging (MRI) techniques are of great importance. In particular, multi-exponential T2 relaxation was shown to be highly sensitive to myelin. The myelin water imaging (MWI) technique allows to separate the T2 decay into short components, specific to myelin water, and long components reflecting the intra- and extracellular water. The myelin water fraction (MWF) is the ratio of the short components to all components. In the brain's white matter (WM), myelin and iron are closely linked via the presence of iron in the myelin generating oligodendrocytes. Iron is known to decrease T2 relaxation times and may therefore mimic myelin. In this study, we investigated if variations in WM iron content can lead to apparent MWF changes. We performed MWI in post mortem human brain tissue prior and after chemical iron extraction. Histology for iron and myelin confirmed a decrease in iron content and no change in myelin content after iron extraction. In MRI, iron extraction lead to a decrease in MWF by 26%-28% in WM. Thus, a change in MWF does not necessarily reflect a change in myelin content. This observation has important implications for the interpretation of MWI findings in previously published studies and future research.

Which Tool Is Best: 3D Scanning or Photogrammetry - It Depends on the Task.

In many educational and clinical settings we are increasingly looking into methodologies for accurate 3D representations of structures and specimens. This is relevant for anatomy teaching, pathology, forensic and anthropological sciences, and various clinical fields. The question then arises which tool best suits the task at hand - both 3D scanning and photogrammetry are options. For the use in medical education the aim is to create 3D models of anatomical specimens with high quality and resolution. Various qualitative and quantitative criteria determine the performance fidelity and results of 3D scanning versus photogrammetry. In our work we found that photogrammetry provides more realistic surface textures and very good geometries for most specimens. 3D surface scanning captures more accurate geometries of complex specimens and in specimens with reflective surfaces. The 3D scanning workflow and capture method is more practical for soft specimens where movement of the sample can lead to distortions. Overall, both methods are highly recommended dependent on the nature of the specimen and the use case of the 3D model.

Real-time ultrasonographic visualization for guided inferior alveolar nerve injection.

OBJECTIVE: The purpose of this study was to develop a methodological technique for the ultrasonographic visualization of the inferior alveolar nerve (IAN) using a novel hockey stick-shaped 8- to 15-MHz transducer in volunteers, followed by simulated IAN scanning and injection in cadavers. STUDY DESIGN: In 20 volunteers, bilateral scans of the IAN nerve were performed with a systematic technique. We recorded times to scan each side and sonographic visibility of the IAN. In 3 cadavers, bilateral scans of the IAN were performed, followed by simulated injection with dye. RESULTS: The IAN was visible in all 40 scans. Mean scanning times were 19.6 seconds (range: 4-54 seconds) for the left side and 30.5 seconds (range: 6-116 seconds) for the right side. In 5 cadaver injections, dye was correctly deposited onto the IAN with the ultrasound technique. CONCLUSIONS: We hypothesize that ultrasound-guided IAN block may be feasible in humans using our technique.

Application and evaluation of automated methods to extract neuroanatomical connectivity statements from free text.

MOTIVATION: Automated annotation of neuroanatomical connectivity statements from the neuroscience literature would enable accessible and large-scale connectivity resources. Unfortunately, the connectivity findings are not formally encoded and occur as natural language text. This hinders aggregation, indexing, searching and integration of the reports. We annotated a set of 1377 abstracts for connectivity relations to facilitate automated extraction of connectivity relationships from neuroscience literature. We tested several baseline measures based on co-occurrence and lexical rules. We compare results from seven machine learning methods adapted from the protein interaction extraction domain that employ part-of-speech, dependency and syntax features. RESULTS: Co-occurrence based methods provided high recall with weak precision. The shallow linguistic kernel recalled 70.1% of the sentence-level connectivity statements at 50.3% precision. Owing to its speed and simplicity, we applied the shallow linguistic kernel to a large set of new abstracts. To evaluate the results, we compared 2688 extracted connections with the Brain Architecture Management System (an existing database of rat connectivity). The extracted connections were connected in the Brain Architecture Management System at a rate of 63.5%, compared with 51.1% for co-occurring brain region pairs. We found that precision increases with the recency and frequency of the extracted relationships. AVAILABILITY AND IMPLEMENTATION: The source code, evaluations, documentation and other supplementary materials are available at http://www.chibi.ubc.ca/WhiteText. CONTACT: paul@chibi.ubc.ca. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics Online.

A method for ultrasonographic visualization and injection of the superior laryngeal nerve: volunteer study and cadaver simulation.

Superior laryngeal nerve block is a valuable technique for provision of upper airway anesthesia. In bilateral scans of 20 volunteers, we developed a technique for ultrasonographic visualization of the superior laryngeal nerve and key anatomical structures using a hockey stick-shaped 8 to 15 MHz transducer (HST15 to 8/20 linear probe, Ultrasonix, Richmond, BC, Canada). Subsequently, we simulated superior laryngeal nerve scanning and injection in bilateral injections in 2 cadavers. Ultrasound-guided in-plane advancement of a needle toward the superior laryngeal nerve and injection of 1 mL of green dye was achieved in all 4 attempts and confirmed by a postprocedural dissection performed by an anatomist. We conclude that ultrasound-guided superior laryngeal nerve block in humans may be feasible.

Brief report: real-time ultrasound-guided spinal anesthesia using Taylor's approach.

The role of ultrasound scanning in spinal anesthesia is principally limited to preprocedure imaging and identification of anatomical structures. We describe our experience with a real-time ultrasound technique for visualization and performance of spinal anesthesia. An initial cadaver study was performed in 5 unembalmed cadavers to develop a technique for real-time performance of ultrasound-guided spinal anesthesia via Taylor's approach (paramedian approach to the L5-S1 interspace). Subsequently, 10 patients scheduled for joint arthroplasty underwent real-time ultrasound-guided spinal anesthesia in the prone position. The relevant anatomy and the needletip were visualized easily and all spinals were effective for joint arthroplasty.

Temporary sequestration of potassium by mitochondria in astrocytes.

Increases in extracellular potassium concentration ([K(+)](o)), which can occur during neuronal activity and under pathological conditions such as ischemia, lead to a variety of potentially detrimental effects on neuronal function. Although astrocytes are known to contribute to the clearance of excess K(+)(o), the mechanisms are not fully understood. We examined the potential role of mitochondria in sequestering K(+) in astrocytes. Astrocytes were loaded with the fluorescent K(+) indicator PBFI and release of K(+) from mitochondria into the cytoplasm was examined after uncoupling the mitochondrial membrane potential with carbonyl cyanide m-chlorophenylhydrazone (CCCP). Under the experimental conditions employed, transient applications of elevated [K(+)](o) led to increases in K(+) within mitochondria, as assessed by increases in the magnitudes of cytoplasmic [K(+)] ([K(+)](i)) transients evoked by brief exposures to CCCP. When mitochondrial K(+) sequestration was impaired by prolonged application of CCCP, there was a robust increase in [K(+)](i) upon exposure to elevated [K(+)](o). Blockade of plasmalemmal K(+) uptake routes by ouabain, Ba(2+), or a mixture of voltage-activated K(+) channel inhibitors reduced K(+) uptake into mitochondria. Also, reductions in mitochondrial K(+) uptake occurred in the presence of mito-K(ATP) channel inhibitors. Rises in [K(+)](i) evoked by brief applications of CCCP following exposure to high [K(+)](o) were also reduced by gap junction blockers and in astrocytes isolated from connexin43-null mice, suggesting that connexins also play a role in K(+) uptake into astrocyte mitochondria. We conclude that mitochondria play a key role in K(+)(o) handling by astrocytes.

Potentiation of NMDA receptor-mediated excitotoxicity linked with intrinsic apoptotic pathway in YAC transgenic mouse model of Huntington's disease.

Evidence suggests N-methyl-D-aspartate receptor (NMDAR) activation is involved in the degeneration of striatal medium-sized spiny neurons (MSNs) in Huntington's disease (HD). We tested the hypothesis that enhanced NMDAR-mediated excitotoxicity is mediated by the mitochondrial-associated apoptotic pathway in cultured MSNs from YAC transgenic mice expressing full-length huntingtin (htt) with a polyglutamine (polyQ) expansion of 46 or 72 (YAC46 or YAC72). NMDAR-mediated Ca(2+) transients and mitochondrial membrane depolarization were significantly increased in YAC compared to wild-type mice MSNs. Inhibitors of the mitochondrial permeability transition (mPT), cyclosporin A and bongkrekic acid, and coenzyme Q10 (an anti-oxidant involved in bioenergetic metabolism) dramatically diminished NMDA-induced cell death and eliminated genotypic differences. In YAC46 MSNs, NMDA stimulated significantly higher activation of caspase-3 and caspase-9 but not caspase-8, and NMDA-induced caspase-3 and -9 activation was markedly attenuated by cyclosporin A. Agents that improve mitochondrial function or inhibit the permeability transition may eliminate increased caspase activation and cell death associated with enhanced NMDAR activity in HD.

Functional NMDA receptor subtype 2B is expressed in astrocytes after ischemia in vivo and anoxia in vitro.

NMDA-type glutamate receptors play a critical role in neuronal synaptogenesis, plasticity, and excitotoxic death. Recent studies indicate that functional NMDA receptors are also expressed in certain glial populations in the normal brain. Using immunohistochemical methods, we detected the presence of the NMDA receptor 2B (NR2B) subunit of the NMDA receptor in neurons but not astrocytes in the CA1 and subicular regions of the rat hippocampus. However, after ischemia-induced neuronal death in these regions, double immunohistochemical labeling revealed that NR2B subunits colocalized with the astrocyte marker glial fibrillary acid protein and with NR1 subunits that are required for functional NMDA receptors. NR2B expression was first observed 3 d after ischemia and reached a peak at 28 d. At 56 d, only a few NR2B-expressing astrocytes were still present. In vitro, when postnatal hippocampal cultures were subjected to 5 min of anoxia, it resulted in NR2B expression on astrocytes in the glial feed layer. Imaging of intracellular calcium with postanoxic cultures and astrocytes isolated acutely from the ischemic hippocampus revealed a rise in intracellular [Ca2+] after stimulation with the specific agonist NMDA. The response could be blocked reversibly with the competitive antagonist 2-amino-5-phosphonovalerate and attenuated by the NR2B-selective antagonist ifenprodil. Control astrocytes were not responsive to NMDA but responded to glutamate. An understanding of the role of astrocytes that express functional NMDA receptors in response to ischemia may guide development of novel stroke therapies.