PT - JOURNAL ARTICLE AU - Manuel S. Malmierca AU - Marco A. Izquierdo AU - Salvatore Cristaudo AU - Olga Hernández AU - David Pérez-González AU - Ellen Covey AU - Douglas L. Oliver TI - A Discontinuous Tonotopic Organization in the Inferior Colliculus of the Rat AID - 10.1523/JNEUROSCI.0238-08.2008 DP - 2008 Apr 30 TA - The Journal of Neuroscience PG - 4767--4776 VI - 28 IP - 18 4099 - http://www.jneurosci.org/content/28/18/4767.short 4100 - http://www.jneurosci.org/content/28/18/4767.full SO - J. Neurosci.2008 Apr 30; 28 AB - Audible frequencies of sound are encoded in a continuous manner along the length of the cochlea, and frequency is transmitted to the brain as a representation of place on the basilar membrane. The resulting tonotopic map has been assumed to be a continuous smooth progression from low to high frequency throughout the central auditory system. Here, physiological and anatomical data show that best frequency is represented in a discontinuous manner in the inferior colliculus, the major auditory structure of the midbrain. Multiunit maps demonstrate a distinct stepwise organization in the order of best frequency progression. Furthermore, independent data from single neurons show that best frequencies at octave intervals of approximately one-third are more prevalent than others. These data suggest that, in the inferior colliculus, there is a defined space of tissue devoted to a given frequency, and input within this frequency band may be pooled for higher-level processing.