Fig. 6.
Connectivity of V1 neurons. (a) Estimated connectivity (ρ,δ)-graphs under vertical grating and blank conditions, with respective number of edges 1160 ± 87 and 1246 ± 87 (95% bootstrap intervals) at 10% FDRII, and 350 ± 29 and 405 ± 30 at 5% FDRII. The node positions represent the individual active channels on the 4×4 mm electrode array, blue and red edges denote positive and negative partial correlations, and a node size is proportional to the number of its connections. (b) Average across neuron pairs of absolute correlation (blue, Eq. 33) and mutual information (red, Eq. 34) with 95% posterior probability bands, as function of grating orientation θ. Larger values imply stronger connectivity. Both measures show maximal values about 20% above their minimum values. (c) Proportions of rejections across θ values of the 5%-level permutation tests that compare connectivities between orientations Δθ apart. Connectivity changes smoothly as a function of Δθ, and the connectivity at an arbitrary orientation θ differs maximally from the connectivity at the orthogonal orientations θ ± Δθ with Δθ = 90.