Prediction outcomes for anterior vertebral body growth modulation surgery from discriminant spatiotemporal manifolds.

PURPOSE: Anterior vertebral body growth modulation (AVBGM) is a minimally invasive surgical technique that gradually corrects spine deformities while preserving lumbar motion. However, identifying suitable patients for surgery is based on clinical judgment and surgical experience. This process would be facilitated by the identification of patients responding to AVBGM prior to surgery using data-driven models trained on previous instrumented cases. METHODS: We introduce a statistical framework for predicting the surgical outcomes following AVBGM in adolescents with idiopathic scoliosis. A discriminant manifold is first constructed to maximize the separation between responsive and non-responsive groups of patients treated with AVBGM for scoliosis. The model then uses subject-specific correction trajectories based on articulated transformations in order to map spine correction profiles to a group-average piecewise-geodesic path. Spine correction trajectories are described in a piecewise-geodesic fashion to account for varying times at follow-up examinations, regressing the curve via a quadratic optimization process. To predict the evolution of correction, a baseline reconstruction is projected onto the manifold, from which a spatiotemporal regression model is built from parallel transport curves inferred from neighboring exemplars. RESULTS: The model was trained on 438 reconstructions and tested on 56 subjects using 3D spine reconstructions from follow-up examinations, with the probabilistic framework yielding accurate results with differences of [Formula: see text] in main curve angulation and a classification rate of 83.2%, and generating models similar to biomechanical simulations. CONCLUSION: The proposed method achieved a higher prediction accuracy and improved the modeling of spatiotemporal morphological changes in surgical patients treated with AVBGM.

Impact of CB1 Receptor Deletion on Visual Responses and Organization of Primary Visual Cortex in Adult Mice.

PURPOSE: The endocannabinoids (eCBs) and their receptors are expressed in the cortex of developing animals where they act as a neuromodulating system during critical stages of brain development such as cell proliferation and migration, and axon guidance. Little is known on the impact of the cannabinoid system on cortical map formation and receptive field properties of cortical sensory neurons. The present study evaluates in vivo the functional organization of the primary visual cortex (V1) of mice lacking cannabinoid CB1R receptor (cnr1-/-). METHODS: Using optical imaging of intrinsic signals, azimuth, and elevation maps of cnr1-/- mice were compared with their wild-type littermates (cnr1+/+). RESULTS: Topographic maps were affected in mutant mice as they exhibited narrower visual field and changes in the shape of V1. CB1R exerted its action in an axis dependent manner as all changes were observed in the azimuth axis. Spatial frequency and contrast sensitivity were also compared between the two groups. Both properties were affected by the chronic lacking of CB1R as mutant mice exhibited a significantly lower contrast sensitivity as well as lower spatial frequency selectivity. CONCLUSIONS: Taken together, these results suggest an important role for CB1R in cortical map formation. Our results also clearly demonstrate the impact of CB1R in the development of visual properties of primary visual cortex neurons. Because psychoactive effects of cannabis consumption on visual experience are mediated mainly through CB1R, our results could possibly explain neuronal mechanisms involved in those perceptual changes.