Organization of FM-FM neurons in IC, MGB, and auditory cortex. A. In IC, each higher harmonic FM frequency band lies within the tonotopically organized IC. No organization of best delays is apparent, as illustrated for the FM3 representation. B. In MGB, FM-FM neurons are segregated from other neurons in a rostral, non-tonotopic part. Neurons tuned to each of the harmonics are clustered, but there is no overall tonotopic organization. There is at least a crude representation of best delays. C. In “FM-FM” and “Dorsal Fringe” areas of auditory cortex, FM-FM neurons are clustered by harmonic sensitivity and organized along an axis of best delay. Used with permission from Portfors and Wenstrup (2001a); © from Elsevier.