R. Veltz, P. Chossat, and O. Faugeras On the Effects on Cortical Spontaneous Activity of the Symmetries of the Network of Pinwheels in Visual Area V1 The Journal of Mathematical Neuroscience (JMN), 5(1), 2015 visual hallucinations invariant torus poincaré–hopf URL, DOI, RIS, BibTex