Figure 2.

Locally averaging fMRI voxels exhibit different tuning than the neurons they sample. A set of neurons (lined up horizontally at the bottom along a single spatial dimension) have a variety of tuning functions (columns of the bottom rectangle). The arrangement of the neurons in cortex is not random. Close-by neurons tend to have similar tuning with respect to features 1–3, but can have different tuning with respect to features 4–6. Locally averaging voxels (top) pool across neurons with different tuning. Local averaging in a voxel will attenuate neuronal selectivities that change rapidly along the cortex (features 4–6), but will approximately preserve selectivities that vary slowly along the cortex (features 1–3).