Primary visual cortex as a saliency map: parameter-free prediction of behavior from V1 physiology

It has been hypothesized that neural activities in the primary visual cortex (V1) represent a saliency map of the visual field to exogenously guide attention. This hypothesis has so far provided only qualitative predictions and their confirmations. We report this hypothesis' first quantitative prediction, derived without free parameters, and its confirmation by human behavioral data. The hypothesis provides a direct link between V1 neural responses to a visual location and the saliency of that location to guide attention exogenously. In a visual input containing many bars, one of them saliently different from all the other bars which are identical to each other, saliency at the singleton's location can be measured by the shortness of the reaction time in a visual search task to find the singleton. The hypothesis predicts quantitatively the whole distribution of the reaction times to find a singleton unique in color, orientation, and motion direction from the reaction times to find other types of singletons. The predicted distribution matches the experimentally observed distribution in all six human observers. A requirement for this successful prediction is a data-motivated assumption that V1 lacks neurons tuned simultaneously to color, orientation, and motion direction of visual inputs. Since evidence suggests that extrastriate cortices do have such neurons, we discuss the possibility that the extrastriate cortices play no role in guiding exogenous attention so that they can be devoted to other functional roles like visual decoding or endogenous attention.Comment: 11 figures, 66 page

Visual Segmentation without Classification in a Model of the Primary Visual Cortex

Stimuli outside classical receptive fields significantly influence the neurons' activities in primary visual cortex. We propose that such contextual influences are used to segment regions by detecting the breakdown of homogeneity or translation invariance in the input, thus computing global region boundaries using local interactions. This is implemented in a biologically based model of V1, and demonstrated in examples of texture segmentation and figure-ground segregation. By contrast with traditional approaches, segmentation occurs without classification or comparison of features within or between regions and is performed by exactly the same neural circuit responsible for the dual problem of the grouping and enhancement of contours

Business plan for third-party platform of medical service for the elderly

The main purpose of this business plan is to build a third-party platform to help the elderly patients, especially those who live in rural areas, monitor their health situation by using intelligent Smart Watches. On the one hand, if they would like to go to a large 3A hospital in a big city, far from their hometown, for further treatment or surgery, we will help them to find the best suitable hospitals and doctors scientifically. On the other hand, we will integrate some medicines industry chains by cutting out the middlemen to decrease the price of some particular medicines through group-buying for our patients, which will make medical market more efficient. With the rise of third-party medical services, the business model of our business plan to solve healthy problems for the elderly has also begun to rise. Before drawing up a business plan for the third-party medical service platform, medical platform staff and specific service population are surveyed, and the results are analyzed. At the same time, the research methods including questionnaire and observation methods are introduced for obtaining some original data. After analyzing the data, we found what kind of problems the elderly and their families face now and what kind of services they need exactly. Finally, we will make a financial plan for five years to help us to predict the profit , working Capital and Cash Requirements.O objetivo principal deste plano de negócios é construir uma plataforma de ajuda aos pacientes idosos, especialmente aqueles que vivem sozinhos em áreas rurais, a monitorizar a sua situação de saúde por meio de relógios inteligentes. Por exemplo, caso queiram ir a um grande hospital 3A, numa cidade grande, longe do seu local de residência, para tratamento ou cirurgia, a plataforma ajudá-los-á, de uma forma científica, a encontrar os hospitais e os médicos mais adequados. A plataforma integrará também algumas redes da indústria farmacêutica eliminando deste modo alguns intermediários o que permitirá uma redução dos preços de alguns medicamentos. O crescimento dos serviços médicos terceirizados levou ao aparecimento de modelos de negócio parecidos ao nosso, a grande diferença do nosso em relação aos restantes consiste no facto de o nosso mercado alvo ser os idosos que vivem sozinhos. Para a construção do nosso plano de negócios analisamos as equipas de plataformas médicas existentes. Ao mesmo, realizamos questionários para obtenção de dados originais. A análise dos dados, permitiu-nos identificar o tipo de problemas que afectam os idosos e as sua famílias e qual o tipo de serviços que necessitam. Por fim, elaboramos um plano financeiro para cinco anos para nos ajudar a prever o lucro, o capital circulante e as necessidades de caixa

Pre-Attentive Segmentation in the Primary Visual Cortex

Stimuli outside classical receptive fields have been shown to exert significant influence over the activities of neurons in primary visual cortexWe propose that contextual influences are used for pre-attentive visual segmentation, in a new framework called segmentation without classification. This means that segmentation of an image into regions occurs without classification of features within a region or comparison of features between regions. This segmentation framework is simpler than previous computational approaches, making it implementable by V1 mechanisms, though higher leve l visual mechanisms are needed to refine its output. However, it easily handles a class of segmentation problems that are tricky in conventional methods. The cortex computes global region boundaries by detecting the breakdown of homogeneity or translation invariance in the input, using local intra-cortical interactions mediated by the horizontal connections. The difference between contextual influences near and far from region boundaries makes neural activities near region boundaries higher than elsewhere, making boundaries more salient for perceptual pop-out. This proposal is implemented in a biologically based model of V1, and demonstrated using examples of texture segmentation and figure-ground segregation. The model performs segmentation in exactly the same neural circuit that solves the dual problem of the enhancement of contours, as is suggested by experimental observations. Its behavior is compared with psychophysical and physiological data on segmentation, contour enhancement, and contextual influences. We discuss the implications of segmentation without classification and the predictions of our V1 model, and relate it to other phenomena such as asymmetry in visual search

Modeling the Olfactory Bulb - Coupled Nonlinear Oscillators

The olfactory bulb of mammals aids in the discrimination of odors. A mathematical model based on the bulbar anatomy and electrophysiology is described. Simulations produce a 35-60 Hz modulated activity coherent across the bulb, mimicing the observed field potentials. The decision states (for the odor information) here can be thought of as stable cycles, rather than point stable states typical of simpler neuro-computing models. Analysis and simulations show that a group of coupled non-linear oscillators are responsible for the oscillatory activities determined by the odor input, and that the bulb, with appropriate inputs from higher centers, can enhance or suppress the sensitivity to partiCUlar odors. The model provides a framework in which to understand the transform between odor input and the bulbar output to olfactory cortex