4 Topographic maps in primary sensory cortices. ( a ) Stimulation sites eliciting sensations in the fi ngers. Sites were largely confi ned to the posterior bank of the central sulcus and postcentral gyrus (Adapted with permission from (Penfi eld and Boldrey 1937 )). ( b ) Infl ated cortical representation of the central sulcus and postcentral gyrus showing fi ngertip activations elicited by each of the digits. There is an orderly progression from the thumb ( d1 ) to the little fi nger ( d5 ) (Adapted with permission from (Schweisfurth et al. 2011 )). ( c ) Tonotopic maps in the auditory cortex. Average relative frequency preference map on the left hemisphere revealing multiple frequency bands within and outside Heschl's gyrus. The enlarged inset shows the mirror-symmetric frequency gradients from high to low to high running across Heschl's gyrus (Adapted from (Striem-Amit et al. 2011 )). ( d ) Retinotopic eccentricity maps in the visual cortex. Medial view of the left hemisphere showing the increase in eccentricity preference from the fovea to the periphery, moving more anteriorly along the calcarine sulcus (Adapted with permission from Wandell and Winawer ( 2011 )