Science education. Educating future scientists.
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Biological Science Disciplines↗
Biomedical subjects
David Mumford
Publications and source records attributed to David Mumford.
Hierarchical Bayesian inference in the visual cortex.
Traditional views of visual processing suggest that early visual neurons in areas V1 and V2 are static spatiotemporal filters that extract local features from a visual scene. The extracted information is then channeled through a feedforward chain of modules in successively higher visual areas for further analysis. Recent electrophysiological recordings from early visual neurons in awake behaving monkeys reveal that there are many levels of complexity in the information processing of the early visual cortex, as seen in the long-latency responses of its neurons. These new findings suggest that activity in the early visual cortex is tightly coupled and highly interactive with the rest of the visual system. They lead us to propose a new theoretical setting based on the mathematical framework of hierarchical Bayesian inference for reasoning about the visual system. In this framework, the recurrent feedforward/feedback loops in the cortex serve to integrate top-down contextual priors and bottom-up observations so as to implement concurrent probabilistic inference along the visual hierarchy. We suggest that the algorithms of particle filtering and Bayesian-belief propagation might model these interactive cortical computations. We review some recent neurophysiological evidences that support the plausibility of these ideas.
Animals↗
Neural activity in early visual cortex reflects behavioral experience and higher-order perceptual saliency.
We report here that shape-from-shading stimuli evoked a long-latency contextual pop-out response in V1 and V2 neurons of macaque monkeys, particularly after the monkeys had used the stimuli in a behavioral task. The magnitudes of the pop-out responses were correlated to the monkeys' behavioral performance, suggesting that these signals are neural correlates of perceptual pop-out saliency. The signals changed with the animal's behavioral adaptation to stimulus contingencies, indicating that perceptual saliency is also a function of experience and behavioral relevance. The evidence that higher-order stimulus attributes and task experience can influence early visual processing supports the notion that perceptual computation is an interactive and plastic process involving multiple cortical areas.
Adaptation, Psychological↗
Recruitment into psychiatry.
BACKGROUND: Despite improvements in psychiatric teaching, British medical schools have never produced enough graduands aiming for psychiatry. AIMS: To inform the strategy for improving recruitment. METHOD: A literature review. RESULTS: The number of psychiatrists required depends on the role of psychiatry, which is constantly changing. The present requirement is about 250-300 per year, including replacements and new posts. The number of psychiatric trainees has always been higher than expected from the career plans of newly qualified doctors, but the number of British graduates passing the Royal College of Psychiatrists' Membership examination has still fallen short, requiring a supplement of foreign medical graduates. The recent 50% expansion in medical students may make this country self-sufficient. CONCLUSIONS: To improve recruitment, the College should focus on influences before and after undergraduate training - the kind of student entering medical school and the factors favouring sustained psychiatric practice after graduation.
Adult↗