The local-global map hypothesis states that locally organized response properties--such as orientation preference--result from visuotopically organized local maps of non-retinotopic response properties. In the tree shrew, the lateral extent of horizontal patchy connections is as much as 80-100% of V1 and is consistent with the length summation property. We argue that neural signals can be transmitted across the entire extent of V1 and this allows the formation of maps at the local scale that are visuotopically organized. We describe mechanisms relevant to the formation of local maps and report modeling results showing the same patterns of horizontal connectivity, and relationships to orientation preference, seen in vivo. The structure of the connectivity that emerges in the simulations reveals a 'hub and spoke' organization. Singularities form the centers of local maps, and linear zones and saddle-points arise as smooth border transitions between maps. These findings are used to present the case for the local-global map hypothesis for tree shrew V1.
Children with asthma in low-income households in Chicago were participants in a school-based mobile van clinic, Mobile C.A.R.E. Our objective was to investigate whether long-term follow-up changed clinical markers and resource utilization. Children were evaluated by a pediatrician in a mobile allergy clinic and classified and treated based on National Asthma Education and Prevention Program (NAEPP) guidelines. Intervention consisted of assessment of allergic environment with avoidance recommendations, institution of appropriate controller therapy and inhaler technique, education on asthma and asthma management, and expectations for asthma control. Over 20,000 children were screened, 2041 were examined at least once, and 677 children had four follow-up visits. With follow-up, there was a decrease in hospitalizations and emergency room visits. Symptomatic markers (daytime and nighttime cough, wheezing, and dyspnea symptoms), frequency of rescue inhaler use, and a quality-of-life score improved from baseline. These findings suggest that ongoing school interventions may reduce resource utilization and improve clinical symptoms. Primary care physicians may be able to deliver specialized care to large numbers of inner-city children with asthma.
The Fourier transform is one of the most important transformations in image processing. A major component of this influence comes from the ability to implement it efficiently on a digital computer. This paper describes a new methodology to perform a fast Fourier transform (FFT). This methodology emerges from considerations of the natural physical constraints imposed by image capture devices (camera/eye). The novel aspects of the specific FFT method described include: 1) a bit-wise reversal re-grouping operation of the conventional FFT is replaced by the use of lossless image rotation and scaling and 2) the usual arithmetic operations of complex multiplication are replaced with integer addition. The significance of the FFT presented in this paper is introduced by extending a discrete and finite image algebra, named Spiral Honeycomb Image Algebra (SHIA), to a continuous version, named SHIAC.
From a few presentations of an object, perceptual systems are able to extract invariant properties such that novel presentations are immediately recognized. This may be enabled by inferring the set of all representations equivalent under certain transformations. We implemented this principle in a neurodynamic model that stores activity patterns representing transformed versions of the same object in a distributed fashion within maps, such that translation across the map corresponds to the relevant transformation. When a pattern on the map is activated, this causes activity to spread out as a wave across the map, activating all the transformed versions represented. Computational studies illustrate the efficacy of the proposed mechanism. The model rapidly learns and successfully recognizes rotated and scaled versions of a visual representation from a few prior presentations. For topographical maps such as primary visual cortex, the mechanism simultaneously represents identity and variation of visual percepts whose features change through time.
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