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- Title
An explanation of contextual modulation by short-range isotropic connections and orientation map geometry in the primary visual cortex.
- Authors
Okamoto, Tsuyoshi; Watanabe, Masataka; Aihara, Kazuyuki; Kondo, Shunsuke
- Abstract
Recent experimental studies on the primary visual cortex have revealed complicated nonclassical neuronal activities. Contextual modulation on orientation-contrast is one typical example of nonclassical neuronal behavior. This modulation by surrounding stimuli in a nonclassical receptive field is mainly thought to be mediated by short- and long-range horizontal connections within the primary visual cortex. Short-range connections are circularly symmetrical and relatively independent of orientation preferences, while long-range connections are patchy, asymmetrical, and orientation specific. Although this modulation can be explained by long-range specific connections qualitatively, recent studies suggest that long-range connections alone may be insufficient with respect to the balance between two types of connections. Here, in order to clarify the role of short-range connections in the process of contextual modulation, we propose a model of the primary visual cortex with isotropic short-range connections and a geometric orientation map. Computational simulations using the model have demonstrated that contextual modulation can be explained by short-range connections alone. This is due to the interaction between the spatial periodicity of orientation domains and the excitatory-inhibitory regions arising from the propagation of activities.
- Subjects
VISUAL cortex; OCCIPITAL lobe; VISION research; CEREBRAL cortex; VISION; RESEARCH
- Publication
Biological Cybernetics, 2004, Vol 91, Issue 6, p396
- ISSN
0340-1200
- Publication type
Article
- DOI
10.1007/s00422-004-0528-9