Regensburg 2007 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
BP: Fachverband Biologische Physik
BP 16: Poster Session I
BP 16.38: Poster
Tuesday, March 27, 2007, 17:00–19:30, Poster D
Shift-Twist-Symmetry and pattern formation in the visual cortex — •Wolfgang Keil1, Michael Schnabel1,2, and Fred Wolf1 — 1Max-Planck-Institut for Dynamics and Self-Organization, Göttingen, D-37073 — 2Bernstein Center for Computational Neuroscience, Göttingen
Neurons in the primary visual cortex preferentially respond to visual stimuli of a particular orientation. Across the cortex, these orientation preferences are arranged in quasiperiodic 2-D patterns, known as orientation maps. Biologically plausible symmetry assumptions have been used successfully to derive a theoretical model which accounts for the emergence of such patterns [1].
Recent measurements have revealed anisotropic coupling statistics in the underlying neural tissue [2], which require the reduction of symmetry in the original model. We discuss consequences of the remaining symmetry (shift-twist-symmetry) in pattern-formation models of the visual cortex. Focussing on the influence of linear and quadratic shift-twist-symmetric coupling terms in the corresponding amplitude equations, the attractors of the dynamics and their stability ranges are calculated. Statistical properties of the spatial arrangement of the emergent structures are compared with recent measurements in tree-shrews. Including additional linear terms improves the agreement with the data. The data exhibits significant signatures of higher-order statistics which are still to be explained by theoretical models.
[1] F. Wolf. Phys. Rev. Lett., 95,208701 (2005)
[2] W.H. Bosking, J. Neurosci., 17, 2112 (1997)