Spontaneous pinwheel annihilation during visual development
Article Abstract:
Visual cortex neurons respond to edge-like stimuli of a certain orientation, and it has long been hypothesized that orientation selectivity occurs during development via the activity-dependent refinement of cortical circuitry. It is argued that the process should leave distinct signatures in emerging spatial patterns of preferred orientations. The smooth progression of preferred orientations is disrupted at the centres of pinwheels. It is demonstrated that the spatial density of pinwheels is constrained by basic principles of symmetry.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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Organization of the visual cortex
Article Abstract:
Contrary to the results of I. Godecke and T. Bonhoeffer, 1996, neurons getting output from a previously sutured eye show independent orientation preferences in the two eyes. This indicates that activity-dependent mechanisms, especially the global constraints due to areal borders and retinotopic structure, determine the organization of the visual cortex. A reverse-suture experiment reveals that orientation maps are restored precisely in cat area 18, if they arise through activity-dependent refined geniculocortical connections.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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The scaling laws of human travel
Article Abstract:
The circulation of bank notes in the US is analyzed to assess human traveling statistics. The results show that human traveling behavior can be mathematically described on many spatiotemporal scales by a two-parameter continuous-time random walk model to a surprising accuracy and also that the human travel on geographical scales is an ambivalent and effectively superdiffusive process.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2006
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