Figure 2.

a, Left, Relaxation rate (R₁ sec⁻¹) as function of cortical depth, averaged within probabilistically defined subdivisions of Brodmann's area 41 (TE1.0, TE1.1, and TE1.2 according to Morosan et al., 2001). Average R₁ within TE1.0 (putative auditory core) decreases steeply from the gray/white boundary (depth fraction 0.0) to a tilted plateau at middle depths (0.3–0.6), then again drops steeply at superficial depths (0.7–1.0). Error bars indicate ±1 SEM over subjects. R₁ within lateral (TE1.1) and medial (TE1.2) subdivisions shows a more gentle monotonic decrease from deep to superficial cortex. For comparison, the left inset is a myelin-stained section of human auditory core and belt cortex (from Wallace et al., 2002, contrast reversed) with a similar profile of myelination. b, Right, Group spherical average R₁ values sampled at 50% of cortical depth and projected onto a single subject's left and right inflated hemispheric surfaces. The auditory core is visible in both hemispheres as a keyhole-shaped hyperintensity maximum running posteromedially to anterolaterally over the medial half of Heschl's gyrus. Hyperintensity maxima can also be observed within the densely myelinated pre- and post-central gyri.