Understanding multivariate brain activity: Evaluating the effect of voxelwise noise correlations on population codes in functional magnetic resonance imaging
Fig 8
Interaction between cTCNC and tuning heterogeneity on population codes.
500 voxels were simulated (see Materials and Methods). A larger value of chomo indicates more homogeneous voxel tuning curves. Note that the simulated voxel tuning curves are identical to neuronal tuning curves when chomo = 1. Panel A illustrates some sample tuning curves of the simulated voxels. Due to the uncertain neuron-to-voxel connections (i.e., linear weighting matrix W), the endowed voxel tuning curves also exhibit irregular forms. Panels B and C illustrate the raw and normalized amount of information as a function of cTCNC under different tuning heterogeneity levels. The raw information is normalized to the condition when cvxs = 0 (panel C). As voxel tuning homogeneity increases, the shape of the functions changes from U-shaped to monotonically decreasing. Panel D illustrates sample voxel tuning curves with different heterogeneity levels.